{"id":15738,"date":"2026-03-03T16:15:24","date_gmt":"2026-03-03T07:15:24","guid":{"rendered":"https:\/\/hanami-web.tokyo.jp\/blog\/?p=15738"},"modified":"2026-03-22T06:28:06","modified_gmt":"2026-03-21T21:28:06","slug":"googl-workspace-post-smtp","status":"publish","type":"post","link":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/","title":{"rendered":"[2026 Latest Version] How to Set Up Google Workspace \u00d7 Post SMTP"},"content":{"rendered":"<p>When using the Post SMTP WordPress plugin with Google Workspace, you can send emails securely and reliably by setting up OAuth authentication.<\/p>\n\n\n\n<p>Currently, Google has disabled password authentication (basic authentication) due to enhanced security measures.<br>Therefore, OAuth settings are required to send emails from WordPress.<\/p>\n\n\n\n<p>This article explains everything from the PostSMTP setup procedure to troubleshooting errors.<br>The Post SMTP plugin is highly recommended as it allows you to obtain email logs for free!<\/p>\n\n\n\n<p>This article is written by HanamiWEB Co., Ltd., a company with extensive experience in WordPress development and operation, and provides a practical explanation that is easy for beginners to understand.<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">table of contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #000000;color:#000000\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewbox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #000000;color:#000000\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewbox=\"0 0 24 24\" version=\"1.2\" baseprofile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%81%93%e3%81%ae%e8%a8%98%e4%ba%8b%e3%81%a7%e3%82%8f%e3%81%8b%e3%82%8b%e4%ba%8b\" >What you will learn from this article<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#postsmtp%e3%83%97%e3%83%a9%e3%82%b0%e3%82%a4%e3%83%b3%e3%81%a8%e3%81%af%ef%bc%9f\" >What is the PostSMTP plugin?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%81%aa%e3%81%9coauth%e8%aa%8d%e8%a8%bc%e3%81%8c%e5%bf%85%e8%a6%81%e3%81%aa%e3%81%ae%e3%81%8b%ef%bc%9f\" >Why is OAuth authentication necessary?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#post_smtp%e3%81%ae%e8%a8%ad%e5%ae%9a%e6%89%8b%e9%a0%86%ef%bc%88google_workspace%e5%af%be%e5%bf%9c%ef%bc%89\" >Post SMTP setup procedure (Google Workspace compatible)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#postsmtp%e3%83%97%e3%83%a9%e3%82%b0%e3%82%a4%e3%83%b3%e3%82%a4%e3%83%b3%e3%82%b9%e3%83%88%e3%83%bc%e3%83%ab%e6%89%8b%e9%a0%86\" >PostSMTP Plugin Installation Instructions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#gmail_api%e3%82%92%e9%81%b8%e6%8a%9e\" >Select Gmail API<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e5%b7%ae%e5%87%ba%e4%ba%ba%e8%a8%ad%e5%ae%9a\" >Sender Settings<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#googleapi%e3%81%ae%e8%a8%ad%e5%ae%9a\" >Google API settings<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#gmailapi%e3%82%92%e8%bf%bd%e5%8a%a0\" >Added Gmail API<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#oauth%e5%90%8c%e6%84%8f%e7%94%bb%e9%9d%a2%e3%82%92%e9%96%8b%e3%81%8f\" >Open the OAuth consent screen<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%82%a2%e3%83%97%e3%83%aa%e3%82%92%e5%85%ac%e9%96%8b\" >Publish your app<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88id%e3%82%92%e3%82%b7%e3%83%bc%e3%82%af%e3%83%ac%e3%83%83%e3%83%88%e3%82%ad%e3%83%bc%e3%82%92%e7%99%ba%e8%a1%8c\" >Issue a client ID and secret key<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#authorized_javascript_prigins%e3%82%92%e8%bf%bd%e5%8a%a0\" >Add Authorized JavaScript Prigins<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#authorized_redirect_url%e3%82%92%e8%bf%bd%e5%8a%a0\" >Add an Authorized redirect URL<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88id%e3%81%a8%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88%e3%82%b7%e3%83%bc%e3%82%af%e3%83%ac%e3%83%83%e3%83%88%e7%99%ba%e8%a1%8c\" >Issuing a client ID and client secret<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e6%9c%80%e5%be%8c%e3%81%ab%e6%8e%a5%e7%b6%9a%e3%82%92%e3%81%97%e3%81%be%e3%81%99\" >Finally, connect<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%83%a1%e3%83%bc%e3%83%ab%e3%81%8c%e9%80%81%e4%bf%a1%e3%81%a7%e3%81%8d%e3%81%aa%e3%81%84%e5%8e%9f%e5%9b%a0%e3%81%a8%e5%af%be%e5%87%a6%e6%b3%95\" >Reasons why emails cannot be sent and how to fix them<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e3%82%88%e3%81%8f%e3%81%82%e3%82%8b%e5%8e%9f%e5%9b%a0\" >Common causes<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#%e5%af%be%e5%87%a6%e6%96%b9%e6%b3%95\" >How to deal with it<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#postsmtp%e8%a8%ad%e5%ae%9a%e3%81%ab%e9%96%a2%e3%81%99%e3%82%8b%e3%81%be%e3%81%a8%e3%82%81\" >Summary of PostSMTP settings<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/hanami-web.tokyo.jp\/blog\/en\/website-running\/googl-workspace-post-smtp\/#postsmtp%e3%81%ab%e9%96%a2%e3%81%99%e3%82%8bqa\" >Q&amp;A regarding PostSMTP<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%81%93%e3%81%ae%e8%a8%98%e4%ba%8b%e3%81%a7%e3%82%8f%e3%81%8b%e3%82%8b%e4%ba%8b\"><\/span>What you will learn from this article<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>How to integrate Post SMTP with Google Workspace<\/li>\n\n\n\n<li>OAuth authentication setup procedure<\/li>\n\n\n\n<li>Troubleshooting steps for when you cannot send an email<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"postsmtp%e3%83%97%e3%83%a9%e3%82%b0%e3%82%a4%e3%83%b3%e3%81%a8%e3%81%af%ef%bc%9f\"><\/span>What is the PostSMTP plugin?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Post SMTP is a WordPress plugin that allows you to securely send emails via an external SMTP server.<br>WordPress&#039;s standard email sending method has a low delivery rate and is often treated as spam, so SMTP settings are essential.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%81%aa%e3%81%9coauth%e8%aa%8d%e8%a8%bc%e3%81%8c%e5%bf%85%e8%a6%81%e3%81%aa%e3%81%ae%e3%81%8b%ef%bc%9f\"><\/span>Why is OAuth authentication necessary?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Google has made the use of OAuth mandatory from 2025 onwards due to enhanced security measures.<\/p>\n\n\n\n<p>Furthermore, Google officially recommends using OAuth-compatible apps.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"post_smtp%e3%81%ae%e8%a8%ad%e5%ae%9a%e6%89%8b%e9%a0%86%ef%bc%88google_workspace%e5%af%be%e5%bf%9c%ef%bc%89\"><\/span>Post SMTP setup procedure (Google Workspace compatible)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Install Post SMTP<\/li>\n\n\n\n<li>Create a project in Google Cloud<\/li>\n\n\n\n<li>Enable the Gmail API<\/li>\n\n\n\n<li>Obtain the OAuth client ID<\/li>\n\n\n\n<li>WordPress settings<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"postsmtp%e3%83%97%e3%83%a9%e3%82%b0%e3%82%a4%e3%83%b3%e3%82%a4%e3%83%b3%e3%82%b9%e3%83%88%e3%83%bc%e3%83%ab%e6%89%8b%e9%a0%86\"><\/span>PostSMTP Plugin Installation Instructions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>This guide explains how to configure the PostSMTP plugin for users of Google Workspace.<br>Once you have installed and activated the PostSMTP plugin, a PostSMTP item will appear in the black sidebar on the left.<br>Click on Dashboard and go to Settings.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"397\" height=\"337\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image.png\" alt=\"\" class=\"wp-image-15739\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image.png 397w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-300x255.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14x12.png 14w\" sizes=\"(max-width: 397px) 100vw, 397px\" \/><\/figure>\n\n\n\n<p>Click Setup the wizard to open the setup screen.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"414\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1-1024x414.png\" alt=\"\" class=\"wp-image-15740\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1-1024x414.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1-300x121.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1-768x310.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1-18x7.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-1.png 1287w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"gmail_api%e3%82%92%e9%81%b8%e6%8a%9e\"><\/span>Select Gmail API<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Select Gmail API and click the Continue button.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"802\" height=\"818\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-2.png\" alt=\"\" class=\"wp-image-15741\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-2.png 802w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-2-294x300.png 294w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-2-768x783.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-2-12x12.png 12w\" sizes=\"(max-width: 802px) 100vw, 802px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e5%b7%ae%e5%87%ba%e4%ba%ba%e8%a8%ad%e5%ae%9a\"><\/span>Sender Settings<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>In From Email, enter the email address of the sender.<br>From Name: Enter the sender&#039;s name.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"641\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3-1024x641.png\" alt=\"\" class=\"wp-image-15742\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3-1024x641.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3-300x188.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3-768x481.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-3.png 1190w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"googleapi%e3%81%ae%e8%a8%ad%e5%ae%9a\"><\/span>Google API settings<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Proceed to set the Client ID and Client Secret at the bottom.<\/p>\n\n\n\n<p>We will use Authorized JavaScript prims and Authorized redirect URLs later.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"908\" height=\"617\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-15.png\" alt=\"\" class=\"wp-image-15754\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-15.png 908w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-15-300x204.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-15-768x522.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-15-18x12.png 18w\" sizes=\"(max-width: 908px) 100vw, 908px\" \/><\/figure>\n\n\n\n<p>Access the Google Cloud Console and configure it.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/console.cloud.google.com\/\">Google Cloud Console is here<\/a><\/div>\n<\/div>\n\n\n\n<p>Click the project selection box in the upper left and click [New Project] to create a new project.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"555\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4-1024x555.png\" alt=\"\" class=\"wp-image-15743\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4-1024x555.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4-300x162.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4-768x416.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4-18x10.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-4.png 1468w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"gmailapi%e3%82%92%e8%bf%bd%e5%8a%a0\"><\/span>Added Gmail API<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>In the left sidebar, under APIs &amp; Services, click Enabled APIs &amp; Services.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"592\" height=\"852\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-25.png\" alt=\"\" class=\"wp-image-15765\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-25.png 592w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-25-208x300.png 208w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-25-8x12.png 8w\" sizes=\"(max-width: 592px) 100vw, 592px\" \/><\/figure>\n\n\n\n<p>Select the library and enable the Gmail API.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"540\" height=\"495\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-26.png\" alt=\"\" class=\"wp-image-15766\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-26.png 540w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-26-300x275.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-26-13x12.png 13w\" sizes=\"(max-width: 540px) 100vw, 540px\" \/><\/figure>\n\n\n\n<p>Search using the Gmail API.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"385\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-1024x385.png\" alt=\"\" class=\"wp-image-15767\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-1024x385.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-300x113.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-768x288.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-1536x577.png 1536w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27-18x7.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-27.png 1571w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Enable it.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"890\" height=\"487\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-28.png\" alt=\"\" class=\"wp-image-15768\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-28.png 890w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-28-300x164.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-28-768x420.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-28-18x10.png 18w\" sizes=\"(max-width: 890px) 100vw, 890px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"oauth%e5%90%8c%e6%84%8f%e7%94%bb%e9%9d%a2%e3%82%92%e9%96%8b%e3%81%8f\"><\/span>Open the OAuth consent screen<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Once you have created a new project, expand the left sidebar and click<br>\u30fbAPIs and services<br>\u30fbOAuth consent screen<br>Select to go to the settings screen.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"736\" height=\"795\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-5.png\" alt=\"\" class=\"wp-image-15744\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-5.png 736w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-5-278x300.png 278w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-5-11x12.png 11w\" sizes=\"(max-width: 736px) 100vw, 736px\" \/><\/figure>\n\n\n\n<p>Click the Start button.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"451\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-1024x451.png\" alt=\"\" class=\"wp-image-15745\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-1024x451.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-300x132.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-768x338.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-1536x676.png 1536w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6-18x8.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-6.png 1732w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Add any string of characters to the app name, set your email address, and then click the [Next] button.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"714\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7-1024x714.png\" alt=\"\" class=\"wp-image-15746\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7-1024x714.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7-300x209.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7-768x535.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-7.png 1090w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Select Outside<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"699\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8-1024x699.png\" alt=\"\" class=\"wp-image-15747\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8-1024x699.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8-300x205.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8-768x524.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-8.png 1051w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Enter your email address again and you&#039;re done.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"641\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9-1024x641.png\" alt=\"\" class=\"wp-image-15748\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9-1024x641.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9-300x188.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9-768x481.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-9.png 1110w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"615\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10-1024x615.png\" alt=\"\" class=\"wp-image-15749\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10-1024x615.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10-300x180.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10-768x461.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-10.png 1102w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%82%a2%e3%83%97%e3%83%aa%e3%82%92%e5%85%ac%e9%96%8b\"><\/span>Publish your app<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Once you have completed the creation, the app will be in test mode, so go to the target tab and click the [Publish app] button repeatedly to publish the app.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"623\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11-1024x623.png\" alt=\"\" class=\"wp-image-15750\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11-1024x623.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11-300x182.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11-768x467.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-11.png 1033w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"424\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12-1024x424.png\" alt=\"\" class=\"wp-image-15751\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12-1024x424.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12-300x124.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12-768x318.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12-18x7.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-12.png 1357w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88id%e3%82%92%e3%82%b7%e3%83%bc%e3%82%af%e3%83%ac%e3%83%83%e3%83%88%e3%82%ad%e3%83%bc%e3%82%92%e7%99%ba%e8%a1%8c\"><\/span>Issue a client ID and secret key<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Next, go to the Clients tab and issue a Client ID and Secret Key.<br>Click the Create Client button.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"350\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13-1024x350.png\" alt=\"\" class=\"wp-image-15752\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13-1024x350.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13-300x103.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13-768x263.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13-18x6.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-13.png 1316w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Select [Web Application] as the application type and give it a name.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"699\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14-1024x699.png\" alt=\"\" class=\"wp-image-15753\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14-1024x699.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14-300x205.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14-768x524.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-14.png 1067w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"authorized_javascript_prigins%e3%82%92%e8%bf%bd%e5%8a%a0\"><\/span>Add Authorized JavaScript Prigins<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Add &quot;Authorized JavaScript origins&quot; in the PostSMTP section to the approved JavaScript origins.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"1006\" height=\"721\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-16.png\" alt=\"\" class=\"wp-image-15755\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-16.png 1006w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-16-300x215.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-16-768x550.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-16-18x12.png 18w\" sizes=\"(max-width: 1006px) 100vw, 1006px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"authorized_redirect_url%e3%82%92%e8%bf%bd%e5%8a%a0\"><\/span>Add an Authorized redirect URL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Add the Authorized redirect URL to the list of authorized redirect URLs.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"728\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17-1024x728.png\" alt=\"\" class=\"wp-image-15756\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17-1024x728.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17-300x213.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17-768x546.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17-18x12.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-17.png 1072w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88id%e3%81%a8%e3%82%af%e3%83%a9%e3%82%a4%e3%82%a2%e3%83%b3%e3%83%88%e3%82%b7%e3%83%bc%e3%82%af%e3%83%ac%e3%83%83%e3%83%88%e7%99%ba%e8%a1%8c\"><\/span>Issuing a client ID and client secret<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Click the Create button and an ID and secret will be issued.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"627\" height=\"697\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-18.png\" alt=\"\" class=\"wp-image-15757\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-18.png 627w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-18-270x300.png 270w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-18-11x12.png 11w\" sizes=\"(max-width: 627px) 100vw, 627px\" \/><\/figure>\n\n\n\n<p>Paste in the PostSMTP Client ID and Client Secret.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"906\" height=\"575\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-19.png\" alt=\"\" class=\"wp-image-15758\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-19.png 906w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-19-300x190.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-19-768x487.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-19-18x12.png 18w\" sizes=\"(max-width: 906px) 100vw, 906px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e6%9c%80%e5%be%8c%e3%81%ab%e6%8e%a5%e7%b6%9a%e3%82%92%e3%81%97%e3%81%be%e3%81%99\"><\/span>Finally, connect<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Click the Connect to Gmail API button.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"320\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21-1024x320.png\" alt=\"\" class=\"wp-image-15760\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21-1024x320.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21-300x94.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21-768x240.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21-18x6.png 18w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-21.png 1141w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>You will be taken to a screen like this, click on Details.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"906\" height=\"583\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-22.png\" alt=\"\" class=\"wp-image-15761\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-22.png 906w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-22-300x193.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-22-768x494.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-22-18x12.png 18w\" sizes=\"(max-width: 906px) 100vw, 906px\" \/><\/figure>\n\n\n\n<p>You will be redirected to a screen like this, but click on the part that says [Hide details] and then click on the text link that says Go to unsecure page.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"886\" height=\"693\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-23.png\" alt=\"\" class=\"wp-image-15762\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-23.png 886w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-23-300x235.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-23-768x601.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-23-15x12.png 15w\" sizes=\"(max-width: 886px) 100vw, 886px\" \/><\/figure>\n\n\n\n<p>You will be taken to a screen like this, so click the Continue button to complete the connection.<\/p>\n\n\n\n<p>*If the security plugin is enabled, communication may be blocked, so it is recommended to temporarily turn off the security plugin before configuring it.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" width=\"1024\" height=\"782\" src=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24-1024x782.png\" alt=\"\" class=\"wp-image-15763\" srcset=\"https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24-1024x782.png 1024w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24-300x229.png 300w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24-768x587.png 768w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24-16x12.png 16w, https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/image-24.png 1068w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%83%a1%e3%83%bc%e3%83%ab%e3%81%8c%e9%80%81%e4%bf%a1%e3%81%a7%e3%81%8d%e3%81%aa%e3%81%84%e5%8e%9f%e5%9b%a0%e3%81%a8%e5%af%be%e5%87%a6%e6%b3%95\"><\/span>Reasons why emails cannot be sent and how to fix them<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e3%82%88%e3%81%8f%e3%81%82%e3%82%8b%e5%8e%9f%e5%9b%a0\"><\/span>Common causes<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Lack of authority<\/li>\n\n\n\n<li>Gmail API is not enabled.<\/li>\n\n\n\n<li>OAuth authentication incomplete<\/li>\n\n\n\n<li>Redirect URL error<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%e5%af%be%e5%87%a6%e6%96%b9%e6%b3%95\"><\/span>How to deal with it<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Check the settings URL<\/li>\n\n\n\n<li>Enable the API<\/li>\n\n\n\n<li>Re-authenticate<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"postsmtp%e8%a8%ad%e5%ae%9a%e3%81%ab%e9%96%a2%e3%81%99%e3%82%8b%e3%81%be%e3%81%a8%e3%82%81\"><\/span>Summary of PostSMTP settings<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>If you want to use POST SMTP with Google Workspace, you must configure OAuth authentication.<br>The setup is a bit complicated, but once configured, it will allow you to send emails reliably.<br>If you have any questions, please feel free to contact us.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"postsmtp%e3%81%ab%e9%96%a2%e3%81%99%e3%82%8bqa\"><\/span>Q&amp;A regarding PostSMTP<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Q. Can I use Google Workspace with POST?<br>A. Yes, it is available if you set up OAuth authentication.<\/p>\n\n\n\n<p>Q. Why is SMTP configuration necessary?<br>A. Because emails sent via WordPress&#039;s standard email service may not be delivered.<\/p>\n\n\n\n<p>Q. Why is OAuth authentication required?<br>A. Because Google recommends OAuth 2.0 for security reasons.<\/p>\n\n\n\n<p>Q. Is SMTP authentication alone not sufficient?<br>A. This is not recommended at present for security reasons.<\/p>\n\n\n\n<p>Q. What is the Gmail API?<br>A. This is a mechanism for using Gmail&#039;s features from external applications.<\/p>\n\n\n\n<p>Q. What could be the reason why I can&#039;t send emails?<br>A. The main causes are authentication settings issues, API not being enabled, and insufficient permissions.<\/p>","protected":false},"excerpt":{"rendered":"<p>Google Workspace\u3067WordPress\u30d7\u30e9\u30b0\u30a4\u30f3\u306ePost SMTP\u3092\u5229\u7528\u3059\u308b\u5834\u5408\u306f\u3001OAuth\u8a8d\u8a3c\u3092\u8a2d\u5b9a\u3059\u308b\u3053\u3068\u3067\u5b89\u5168\u304b\u3064\u78ba\u5b9f\u306b\u30e1\u30fc\u30eb\u9001\u4fe1\u304c\u53ef\u80fd\u3067\u3059\u3002 \u73fe\u5728\u3001Google\u306f\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u5f37\u5316\u306b\u3088\u308a\u3001\u30d1\u30b9\u30ef\u30fc [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":15782,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"content-type":"","_uag_custom_page_level_css":"","footnotes":""},"categories":[6],"tags":[],"class_list":["post-15738","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-website-running"],"blocksy_meta":[],"aioseo_notices":[],"uagb_featured_image_src":{"full":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1.png",720,540,false],"thumbnail":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1-150x150.png",150,150,true],"medium":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1-300x225.png",300,225,true],"medium_large":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1.png",720,540,false],"large":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1.png",720,540,false],"1536x1536":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1.png",720,540,false],"2048x2048":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1.png",720,540,false],"trp-custom-language-flag":["https:\/\/hanami-web.tokyo.jp\/blog\/wp-content\/uploads\/2026\/03\/Other-1-16x12.png",16,12,true]},"uagb_author_info":{"display_name":"\u682a\u5f0f\u4f1a\u793eHanamiWEB \u4ee3\u8868\u53d6\u7de0\u5f79 \u677e\u6d66\u307f\u3055","author_link":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/author\/hanami\/"},"uagb_comment_info":0,"uagb_excerpt":"Google Workspace\u3067WordPress\u30d7\u30e9\u30b0\u30a4\u30f3\u306ePost SMTP\u3092\u5229\u7528\u3059\u308b\u5834\u5408\u306f\u3001OAuth&hellip;","brizy_media":[],"_links":{"self":[{"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/posts\/15738","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/comments?post=15738"}],"version-history":[{"count":9,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/posts\/15738\/revisions"}],"predecessor-version":[{"id":15794,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/posts\/15738\/revisions\/15794"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/media\/15782"}],"wp:attachment":[{"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/media?parent=15738"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/categories?post=15738"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hanami-web.tokyo.jp\/blog\/en\/wp-json\/wp\/v2\/tags?post=15738"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}