{"id":3860,"date":"2024-04-16T10:49:25","date_gmt":"2024-04-16T10:49:25","guid":{"rendered":"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-504-5-7-4-solved\/"},"modified":"2026-06-18T08:39:59","modified_gmt":"2026-06-18T08:39:59","slug":"how-to-fix-smtp-email-error-504-5-7-4-solved","status":"publish","type":"post","link":"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-504-5-7-4-solved\/","title":{"rendered":"SMTP Error 504 5.7.4: What It Means, Why It Happens, and How to Fix It"},"content":{"rendered":"\n<p><a href=\"https:\/\/www.warmy.io\/blog\/what-is-smtp-and-how-does-the-smtp-server-work\/\" target=\"_blank\" rel=\"noopener noreferrer\">Simple Mail Transfer Protocol (SMTP)<\/a> is the foundation for all email communication. It dictates the framework for sending and receiving messages worldwide on various networks. Additionally, SMTP supports messaging for both personal and professional communications, basically handling the majority of daily information exchanges.<\/p>\n\n\n\n<p>SMTP error 504 5.7.4 means the receiving mail server rejected your authentication request because the method your email client used is either unrecognized or not supported. In plain terms: your email wasn&#8217;t sent because the server and client couldn&#8217;t agree on how to verify your identity. The fix almost always involves updating your SMTP authentication settings to use TLS on port 587 or SSL on port 465 \u2014 and if you&#8217;re troubleshooting multiple delivery issues at once, Warmy&#8217;s <a href=\"https:\/\/www.warmy.io\/blog\/smtp-error-codes-and-messages\/\" target=\"_blank\" rel=\"noopener noreferrer\">SMTP error codes reference<\/a> covers the full range of error types and how to resolve each one.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What is SMTP Email Error 504 5.7.4?<\/h2>\n\n\n\n<p>SMTP Email Error 504 5.7.4 denotes issues with the authentication process during email delivery. When you come across this error, it means <a href=\"https:\/\/www.warmy.io\/blog\/mastering-email-deliverability-the-modern-guide-to-authentication-and-inbox-warm-up\/\" target=\"_blank\" rel=\"noopener noreferrer\">authentication processes<\/a> are either improperly configured or unsupported\u2014which prevents the SMTP server from processing an email.<\/p>\n\n\n\n<p>Unlike some generic SMTP errors that stem from server overload or routing issues, error 504 5.7.4 is specifically an authentication failure. That means the problem is almost always fixable on your end \u2014 once you know where to look. This guide gives you the exact steps.<\/p>\n\n\n\n<p>Those who experience this error will see notifications that specifically mention issues with authentication. Typical error messages include the following:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u201c504 5.7.4 Unrecognized authentication type\u201d<\/strong> indicates that the email client\u2019s attempted authentication mechanism is not supported or recognized by the SMTP server.<\/li>\n\n\n\n<li><strong>\u201c504 5.7.4 Authentication mechanism is too weak\u201d<\/strong> may arise when the server demands a more secure authentication method than what is currently being used.<\/li>\n\n\n\n<li><strong>\u201c504 5.7.4 Command parameter not implemented\u201d<\/strong> may sometimes be associated with authentication command parameters that the server is unable to process.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Quick Reference: Error Variants and What They Mean<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Error Message<\/th><th>Root Cause<\/th><th>First Fix<\/th><\/tr><\/thead><tbody><tr><td><strong>504 5.7.4 Unrecognized authentication type<\/strong><\/td><td>Client using unsupported auth method<\/td><td>Switch to STARTTLS or LOGIN auth<\/td><\/tr><tr><td><strong>504 5.7.4 Authentication mechanism is too weak<\/strong><\/td><td>Server requires higher-security method<\/td><td>Enable TLS, disable PLAIN\/CRAM-MD5<\/td><\/tr><tr><td><strong>504 5.7.4 Command parameter not implemented<\/strong><\/td><td>Auth command syntax not supported by server<\/td><td>Update client SMTP config or contact host<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">So why does SMTP Email Error 504 5.7.4 occur?<\/h2>\n\n\n\n<p>There are many possible reasons and scenarios why this particular error occurs, and we\u2019re going to discuss each one.&nbsp;&nbsp;<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. Authentication failures<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Unsupported authentication method<\/h4>\n\n\n\n<p>The most common scenario is a mismatch between the authentication mechanism your client sends and what the server accepts. For example, your client may attempt to use CRAM-MD5 or PLAIN authentication while the server only accepts STARTTLS or OAuth2. Modern mail servers increasingly require encrypted authentication flows \u2014 if your client is configured for older methods, the connection will be rejected.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Incorrect authentication settings<\/h4>\n\n\n\n<p>If the <a href=\"https:\/\/www.warmy.io\/blog\/why-do-you-need-to-configure-spf-dkim-dmarc-and-how-to-set-them\" target=\"_blank\" rel=\"noopener noreferrer\">authentication settings<\/a> on the server or client\u2019s side are misconfigured, this error might occur. This isn\u2019t just about typing the wrong username and password. It may involve incorrect setup of security tokens, key files, or other authentication credentials.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\ud83d\udca1 Pro Tip: Always use app-specific passwords (not your main account password) when configuring third-party SMTP clients with Gmail or Yahoo. Main passwords are increasingly blocked for programmatic access.<\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">2. Configuration errors<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Server configuration issues<\/h4>\n\n\n\n<p>Another possible reason behind the error is the email server might be misconfigured. This prevents it from recognizing or allowing the authentication method requested by the client. This can also include incorrect SMTP settings or authentication methods that should be enabled or disabled.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Client configuration<\/h4>\n\n\n\n<p>The client may be set to use an authentication method that the server doesn\u2019t support or isn\u2019t configured to handle. If the client\u2019s security settings don\u2019t match the server\u2019s requirements, authentication failures can occur.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Protocol mismatches<\/h4>\n\n\n\n<p>A common real-world cause is using port 25 (which is often blocked or unencrypted) instead of port 587 with STARTTLS or port 465 with SSL\/TLS. The wrong port selection forces a protocol mismatch that surfaces as a 504 5.7.4 error.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">3. Server limitations<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Outdated server software<\/h4>\n\n\n\n<p>When more advanced clients try to connect using settings that the server is unable to handle, they may see this error because the server software is out of date and does not support the more recent authentication methods.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Restrictive server policies<\/h4>\n\n\n\n<p>Using specific authentication techniques may also be prohibited by the stringent security standards of some servers. Certain servers, for instance, might only accept encrypted passwords and reject requests that try to use a less secure technique.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Step-by-step guide to handle SMTP Email Error 504 5.7.4<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Gmail<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Log in to your Gmail account.<\/li>\n\n\n\n<li>Select \u201cSee all settings\u201d from the gear icon.<\/li>\n\n\n\n<li>Go to Accounts and Import.&nbsp;<\/li>\n\n\n\n<li>From the \u2018Accounts and Import\u2019 menu, select the \u2018Send mail as\u2019 column. Then click \u2018Add another email address.\u2019<\/li>\n\n\n\n<li>Enter your name and the email address you want to send from in the popup box. If you would like to administer this account using your primary Gmail account, make sure that \u2018Treat as an alias\u2019 is ticked.<\/li>\n\n\n\n<li>Under SMTP settings, do the following:\n<ul class=\"wp-block-list\">\n<li>SMTP Server: Enter smtp.gmail.com.<\/li>\n\n\n\n<li>Username: Your full Gmail address (including @gmail.com).<\/li>\n\n\n\n<li>Password: Use an App Password \u2014 <a href=\"https:\/\/support.google.com\/accounts\/answer\/185833\" rel=\"noopener\" target=\"_blank\" rel=\"noopener noreferrer\">generate one here<\/a> if 2-Step Verification is on<\/li>\n\n\n\n<li>Port: 587 (STARTTLS) or 465 (SSL) \u2014 avoid port 25<\/li>\n\n\n\n<li>Authentication: Select Secured connection using TLS (recommended)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Verify that \u201cSecured connection using TLS\u201d or \u201cSecured connection using SSL\u201d is selected for authentication.<\/li>\n\n\n\n<li>Conserve modifications. Select \u2018Add Account\u2019 and adhere to the instructions to verify the email address via a verification email.<\/li>\n<\/ul>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\ud83d\udca1 Pro Tip: Gmail blocks &#8216;less secure app&#8217; sign-ins for all accounts. If you&#8217;re connecting a third-party email client or ESP, you must use OAuth2 or generate a Google App Password \u2014 your regular Gmail password will be rejected.<\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">Outlook<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Access the Account Settings. Navigate to File &gt; Account Settings &gt; Manage Profiles after opening Outlook.<\/li>\n\n\n\n<li>Select \u201cEmail Accounts\u201d from the Mail Setup box.<\/li>\n\n\n\n<li>Change account. Click \u201cChange\u201d after selecting your email account. Check the Outgoing Mail Server (SMTP) under \u201cServer Information.\u201d It should be configured in accordance with your email provider (for example, smtp-mail.outlook.com for Outlook).<\/li>\n\n\n\n<li>Next, go to additional settings. Select the \u201cOutgoing Server\u201d tab by clicking on \u201cMore Settings.\u201d Check the box next to \u201cMy outgoing server (SMTP) requires authentication.\u201d<\/li>\n\n\n\n<li>Select the \u2018Advanced\u2019 tab. Use port 587 for SMTP then choose \u201cTLS\u201d for the kind of encrypted connection.<\/li>\n\n\n\n<li>After selecting \u201cNext\u201d to allow Outlook to test your settings, click \u201cOK\u201d to close the More Settings window.<\/li>\n\n\n\n<li>Click \u201cFinish\u201d and restart Outlook when the test has been successful.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Yahoo!<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Visit Yahoo! Mail, log in, and proceed to your account details.&nbsp;<\/li>\n\n\n\n<li>Click on \u201cAccount Security.\u201d<\/li>\n\n\n\n<li>Create app password. If two-factor authentication is enabled, you might need to create an app-specific password to utilize it in your email client rather than your main password.<\/li>\n\n\n\n<li>Configure email client by doing the following:\n<ul class=\"wp-block-list\">\n<li>SMTP Server: smtp.mail.yahoo.com.<\/li>\n\n\n\n<li>Port: Use 465 with SSL or 587 with TLS.<\/li>\n\n\n\n<li>Username: Your full Yahoo email address.<\/li>\n\n\n\n<li>Password: The app password you generated, or your regular password if you don\u2019t have two-factor authentication enabled.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Save settings. Ensure your email client uses these settings and re-test sending an email.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">For other clients<\/h3>\n\n\n\n<p>If you&#8217;re using a custom SMTP setup \u2014 such as a self-hosted server, SendGrid, Amazon SES, or Mailgun \u2014 the troubleshooting approach is the same but configuration options vary. Warmy.io supports SMTP warmup for custom SMTP, Amazon SES, SendGrid, Mailgun, Brevo, Zoho, and more \u2014 see the full list of supported providers.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><b>Verify SMTP settings.<\/b> To determine the proper SMTP settings, including server address, port, and whether SSL\/TLS is required, consult the documentation for your particular email platform.<\/li>\n\n\n\n<li><b>Verify authentication.<\/b> Make sure the email client is set up for authentication and that the username and password you are using are accurate.<\/li>\n\n\n\n<li><b>Update or reinstall. <\/b>Updating the email client to the most recent version or reinstalling it may help fix configuration issues if problems continue.<\/li>\n\n\n\n<li><b>Contact support. <\/b>To make sure your settings are accurate and accepted by the server, contact the support staff of your email provider if the error persists.<\/li>\n<\/ul>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\ud83d\udcec Not sure if your SMTP settings are hurting your deliverability? <a href=\"https:\/\/www.warmy.io\/free-tools\/email-deliverability-test\" target=\"_blank\" rel=\"noopener noreferrer\">Run a free Email Deliverability Test<\/a> to check inbox placement across Gmail, Outlook, and Yahoo \u2014 and verify your SPF, DKIM, and DMARC records are correctly configured.<\/p>\n<\/blockquote>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe title=\"The Complete Tool For Email Deliverability: Meet Warmy.io!\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/jFXzuA-F-Nc?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Why Authentication Errors Like 504 5.7.4 Hurt More Than Just One Email<\/h2>\n\n\n\n<p>SMTP error 504 5.7.4 doesn&#8217;t just block a single message \u2014 it signals to receiving servers that something is wrong with your sending setup. When authentication failures happen repeatedly, mail servers may start flagging your domain, which can lower your sender reputation even after the technical issue is resolved.<\/p>\n\n\n\n<p>This is especially important if you&#8217;re running outbound campaigns or using your domain for business email. A misconfigured SMTP setup can create deliverability problems that persist for weeks \u2014 even after the underlying error is fixed \u2014 because damaged sender reputation doesn&#8217;t recover instantly.<\/p>\n\n\n\n<p>To understand how a<a href=\"https:\/\/www.warmy.io\/blog\/mastering-email-deliverability-the-modern-guide-to-authentication-and-inbox-warm-up\/\" target=\"_blank\" rel=\"noopener noreferrer\">uthentication processes<\/a> relate to overall deliverability, and how to structure a long-term approach, Warmy&#8217;s <a href=\"https:\/\/www.warmy.io\/free-tools\/email-deliverability-guide\" target=\"_blank\" rel=\"noopener noreferrer\">email deliverability guide<\/a> covers the full picture.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\ud83d\udca1 Pro Tip: After fixing a 504 5.7.4 error, don&#8217;t immediately send high volumes. Ramp up gradually over 1\u20132 weeks to rebuild any reputation loss. An email warmup tool automates this ramp-up and helps you monitor inbox placement as you recover.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">Tackling SMTP Email Errors and email warmup go hand-in-hand<\/h2>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/03\/11092902\/403shots_so-1.webp\" alt=\"Graph showing email warmup performance with a daily sent and received volume of -2004. It features deliverability statistics for three weeks in June, detailing inbox placement (1,200), spam (200), and displaying traffic volume trends.\" title=\"\"><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p>To eliminate the SMTP 504 5.7.4, one should closely delve into the email authentication methods\u2019 peculiarities and make sure that both the email server and client are configured correctly to get access to supported protocols. Whether you deal with your emails through Gmail, Outlook, or Yahoo!, or through various less-known platforms, you must still align SMTP settings with server capacities and security standards.<\/p>\n\n\n\n<p>It\u2019s easy to think that once you\u2019ve completed the steps discussed above that you\u2019re already in the clear. However, we challenge you to take the next step\u2014one that is designed to change your email marketing game.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How Warmy can help get rid of SMTP Errors<\/h2>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"825\" height=\"527\" src=\"https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2024\/07\/Screenshot_5.png\" alt=\"dashboard\" class=\"wp-image-7063\" title=\"\" srcset=\"https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2024\/07\/Screenshot_5.png 825w, https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2024\/07\/Screenshot_5-300x192.png 300w, https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2024\/07\/Screenshot_5-768x491.png 768w\" sizes=\"auto, (max-width: 825px) 100vw, 825px\" \/><\/figure>\n\n\n\n<p><a href=\"https:\/\/www.warmy.io\/\" target=\"_blank\" rel=\"noopener noreferrer\">Warmy<\/a> is an AI-driven email warmup and deliverability platform that automatically builds your sender reputation, improves inbox placement, and keeps your emails out of spam \u2014 no technical expertise required.<\/p>\n\n\n\n<p><b>You see, avoiding or preventing SMTP errors is one thing. But enhancing your email deliverability as a whole will lead you to long-term success.<\/b><\/p>\n\n\n\n<p>Properly warmed-up accounts are unlikely to be flagged by email service providers for suspicious activity, which can cause such SMTP errors.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Comprehensive email deliverability test<\/strong><\/h3>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/03\/11093353\/562shots_so-1.webp\" alt=\"A digital dashboard titled Email Deliverability Test shows a summary of results. A circular graph indicates 9 hours to completion. Charts below display placement percentages across platforms like Gmail, Outlook, and Yahoo.\" title=\"\"><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p>Warmy.io lets you not only do the warming process but also provides other tools that help with email deliverability. It offers free <a href=\"https:\/\/www.warmy.io\/free-tools\/email-deliverability-test\" target=\"_blank\" rel=\"noopener noreferrer\">email deliverability tests<\/a> that allow you to test your emails and see if everything is working fine before you start any campaign to avoid any related issues.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Free SPF and DMARC Record Generators<\/strong><\/h3>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/03\/11093355\/848shots_so.webp\" alt=\"A website interface titled Free DMARC Record Generator with a form to enter a domain for generating a DMARC record. Below the title are navigation buttons for Domain, ESP, Email, and DMARC value. A Next button is at the bottom.\" title=\"\"><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p>Last but not least, it provides a fancy tool to generate <a href=\"https:\/\/www.warmy.io\/free-tools\/spf-generator\" target=\"_blank\" rel=\"noopener noreferrer\">SPF<\/a> and <a href=\"https:\/\/www.warmy.io\/free-tools\/dmarc-generator\" target=\"_blank\" rel=\"noopener noreferrer\">DMARC<\/a> records. These records are needed for email authentication and email protection as they allow controlling the email that claims to be sent from your domain.\u00a0\\<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">AI-Driven Email Warmup<\/h3>\n\n\n\n<p>Warmy uses <a href=\"https:\/\/www.warmy.io\/product\/ai\" target=\"_blank\" rel=\"noopener noreferrer\">Adeline AI<\/a> \u2014 a dedicated AI engine built specifically for email deliverability \u2014 to automate your warmup schedule, adjust sending patterns based on real inbox placement data, and monitor reputation across providers. Unlike basic warmup tools that just send emails back and forth, Warmy warms up with real clicks, across a network of over 1 million active mailboxes, producing verifiable engagement data.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"965\" height=\"641\" src=\"https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2026\/06\/Adeline-AI.png\" alt=\"Adeline AI\" class=\"wp-image-6958\" title=\"\" srcset=\"https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2026\/06\/Adeline-AI.png 965w, https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2026\/06\/Adeline-AI-300x199.png 300w, https:\/\/www.warmy.io\/blog\/wp-content\/uploads\/2026\/06\/Adeline-AI-768x510.png 768w\" sizes=\"auto, (max-width: 965px) 100vw, 965px\" \/><\/figure>\n\n\n\n<p>All these features make Warmy.io an all-in tool for managing email and ensuring it reaches your recipient. There\u2019s a <a href=\"https:\/\/app.warmy.io\/signup\" rel=\"noopener\" target=\"_blank\" rel=\"noopener noreferrer\">free 7-day trial<\/a> you can explore\u2014and trust us, you\u2019ll want to make the most of it once you see what\u2019s inside.&nbsp;<\/p>\n\n\n\n<p>\ud83d\udcdc<b> Related articles:<\/b><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-504-solved\/\" target=\"_blank\" rel=\"noopener noreferrer\">SMTP Email Error 504 \u2013 How to Resolve [SOLVED]<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-504-5-7-4-solved\/\" target=\"_blank\" rel=\"noopener noreferrer\">SMTP Email Error 504 5.7.4 \u2013 How to Resolve [SOLVED]<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-504-5-5-2-solved\/\" target=\"_blank\" rel=\"noopener noreferrer\">SMTP Email Error 504 5.5.2 \u2013 How to Resolve [SOLVED]<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Simple Mail Transfer Protocol (SMTP) is the foundation for all email communication. It dictates the framework for sending and receiving messages worldwide on various networks. Additionally, SMTP supports messaging for both personal and professional communications, basically handling the majority of daily information exchanges. SMTP error 504 5.7.4 means the receiving mail server rejected your authentication [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":7276,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[104],"tags":[],"class_list":["post-3860","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-email-deliverability"],"acf":[],"lang":"en","translations":{"en":3860},"pll_sync_post":[],"_links":{"self":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3860","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/comments?post=3860"}],"version-history":[{"count":4,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3860\/revisions"}],"predecessor-version":[{"id":7281,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3860\/revisions\/7281"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/media\/7276"}],"wp:attachment":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/media?parent=3860"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/categories?post=3860"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/tags?post=3860"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}