{"id":3866,"date":"2024-04-17T12:30:58","date_gmt":"2024-04-17T12:30:58","guid":{"rendered":"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-552-5-7-0-solved\/"},"modified":"2026-04-04T13:34:44","modified_gmt":"2026-04-04T13:34:44","slug":"how-to-fix-smtp-email-error-552-5-7-0-solved","status":"publish","type":"post","link":"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-552-5-7-0-solved\/","title":{"rendered":"SMTP Error 552 5.7.0: Content Rejected \u2014 Causes and How to Resolve It"},"content":{"rendered":"<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<\/a> is an essential part of email communication. Once an email is written and sent, the SMTP server is responsible for forwarding and ensuring its secure reception.<\/p>\n<p>So when SMTP errors occur, it hinders the effective sending and receiving of emails. The SMTP Email Error 552 5.7.0 is a message rejection due to several reasons\u2014including violating policies and exceeding the size of the receiving server.<\/p>\n<p>The disruption of the email-sending process results in inhibited communication and workflow, affecting productivity. The error must be well understood to detect the violations and, thereafter, promptly correct to continue with email activity.<\/p>\n<p><iframe width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/_0RBzuwDM5k\" frameborder=\"0\" allowfullscreen allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\"><\/iframe><\/p>\n<h2>Understanding SMTP Email Error 552 5.7.0<br \/>\n<\/h2>\n<p>SMTP Email Error 552 5.7.0 occurs with email users who could be using one of the various email systems, or those tracking and correcting such failures on the administrator\u2019s side.<\/p>\n<p>Below is a brief overview of how this issue appears in common email systems and what it generally means.<\/p>\n<ul>\n<li>An error message in Microsoft Outlook: \u201cServer error: \u2018552 5.7.0 This message was blocked because its content presents a potential security issue.\u201d<\/li>\n<li>In addition, Gmail\u2019s bounce-back from the server \u201c552-5.7.0 Our system detected an illegal attachment on your message. Please visit our guidelines.\u201d could look this way in their notification, such as<\/li>\n<li>Yahoo Mail: \u201cFailure Notice: 552 Message size exceeds maximum permitted\u201d.<\/li>\n<\/ul>\n<h2>Key reasons behind SMTP Email Error 552 5.7.0<\/p>\n<\/h2>\n<h3>Content policy violations<br \/>\n<\/h3>\n<h4>Attachments and file types<\/h4>\n<p>The kinds of files that can be attached to emails are subject to stringent regulations on many email servers. Blocking executable files (.exe,.scr, etc.) is widespread practice because these files are frequently linked to harmful malware. Likewise, excessively big files may also result in rejections.<\/p>\n<h4>Spammy content<\/h4>\n<p>The server may automatically reject emails that seem to be spam. This can include emails with deceptive subject lines, an excessive number of links, or terms that are prohibited and frequently used in phishing or spam campaigns.<\/p>\n<h4>Formatting and structure<\/h4>\n<p>Rejections can also result from emails that are badly formatted or created in a way that sets off spam filters (such as base64 encoding in the message body). This includes utilizing specific HTML elements or styles that are frequently connected to unsolicited emails.<\/p>\n<h3>Security settings and concerns<br \/>\n<\/h3>\n<h4>Virus and malware detection<\/h4>\n<p>Attachments are scanned by antivirus software on contemporary email servers to check for viruses and malware. To safeguard both the sender and the recipient from possible harm, the server will reject a message containing an attachment if it is deemed harmful. To further protect your email systems, follow this <a href=\"https:\/\/www.wiz.io\/academy\/what-is-api-security\" rel=\"noopener\" target=\"_blank\" rel=\"noopener noreferrer\">API security checklist<\/a> to secure integrations and prevent potential threats.<\/p>\n<h4>Errors with DMARC, SPF, and DKIM<\/h4>\n<p>These email authentication techniques are meant to confirm the sender\u2019s identity and stop email spoofing. Emails that don\u2019t follow these protocols may be denied because the receiving server won\u2019t be able to confirm that the message is from a reliable source.<\/p>\n<p><strong>\ud83d\udd16 Relevant Reading:<\/strong> <a href=\"https:\/\/www.warmy.io\/blog\/spf-dkim-and-dmarc-what-they-are-and-why-you-should-care\/\" target=\"_blank\" rel=\"noopener noreferrer\">SPF, DKIM, and DMARC: What They Are and Why You Should Care<\/a><\/p>\n<h4>IP reputation and blacklisting<\/h4>\n<p>Servers may automatically reject emails received from IP addresses that have been blacklisted as a result of prior malicious activity. This contains IPs that are well-known for harboring malware or for transmitting spam.\u00a0<\/p>\n<p>Check if you are blacklisted for free <a href=\"https:\/\/www.warmy.io\/free-tools\/email-deliverability-test\" target=\"_blank\" rel=\"noopener noreferrer\">here.<\/a><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"A website tool interface for testing email deliverability, showing fields to enter email addresses, a sample message, and a blue button labeled Check your email deliverability on a beige background.\" height=\"600\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2024\/06\/22070553\/test-1.png\" width=\"800\" title=\"\"><\/p>\n<h2>Step-by-step solutions to resolve SMTP Email Error 552 5.7.0<\/h2>\n<h3>Gmail<\/h3>\n<ol>\n<li><strong>Verify email size.<\/strong> Make sure the combined size of your email and its attachments doesn\u2019t go above Gmail\u2019s 25 MB limit. If so, consider use links to Google Drive rather than straight attachments.<\/li>\n<li><strong>Examine the different types of attachments.<\/strong> Remove those that can be dangerous (scripts or executables, for example). Share files via reliable cloud storage services instead, and include a link in your email.<\/li>\n<li><strong>Check for malware. <\/strong>To prevent sending malicious files, scan your attachments with antivirus software before sending.<\/li>\n<li><strong>Check the content of the email.<\/strong> Steer clear of spammy elements like a lot of links, wording that is too promotional, or deceptive subject lines.<\/li>\n<\/ol>\n<h3>Outlook<\/h3>\n<ol>\n<li><strong>Modify email format.<\/strong> Make your email easier to read by eliminating any complicated HTML components or scripts that could be interpreted as suspicious.<\/li>\n<li><strong>Respect attachment policies.<\/strong> Verify that your files adhere to Microsoft\u2019s safety requirements by reviewing Outlook\u2019s attachment policies.<\/li>\n<li><strong>Employ email authentication.<\/strong> To increase deliverability and authenticate your emails, make sure your email account is properly configured with SPF, DKIM, and DMARC records.<\/li>\n<li><strong>Check server settings. <\/strong>To make sure you\u2019re in compliance with your hosting provider\u2019s sending policies, check the server settings or speak with them if you use Outlook with a custom domain.<\/li>\n<\/ol>\n<h3>Yahoo Mail<\/h3>\n<ol>\n<li>\n<p><strong>Reduce email size.<\/strong>\u00a0If your email exceeds Yahoo\u2019s size limits, try compressing attachments or splitting your content into multiple emails.<\/p>\n<\/li>\n<li>\n<p><strong>Check blacklists.<\/strong>\u00a0Ensure your sending IP is not blacklisted. If it is, you may need to contact your ISP or use a different network to send your email.<\/p>\n<\/li>\n<li>\n<p><strong>Avoid spam triggers. <\/strong>Refrain from using excessive bold or colored fonts, and ensure the email does not resemble common spam characteristics.<\/p>\n<\/li>\n<\/ol>\n<h3>Technical guidance to align email content and settings<br \/>\n<\/h3>\n<ol>\n<li>\n<p><strong>Content review and modification.<\/strong> Regularly review your email content for anything that might trigger spam filters. Adapt the language and formatting to be more professional and less spam-like. You can easily check it with <a href=\"https:\/\/www.warmy.io\/free-tools\/template-checker\" target=\"_blank\" rel=\"noopener noreferrer\">Warmy\u2019s free template checker.<\/a><\/p>\n<\/li>\n<li>\n<p><strong>Security configuration verification.<\/strong>\u00a0Regularly update and verify your email security settings. Ensure that antivirus and antimalware solutions are active and scanning your emails before they are sent.<\/p>\n<\/li>\n<li>\n<p><strong>Monitor feedback loops. <\/strong>Set up feedback loops with major ISPs to receive notifications when your emails are marked as spam or blocked. This feedback can help you adjust your email practices accordingly.<\/p>\n<\/li>\n<\/ol>\n<p>Choosing \u2018System email only\u2019 permits only essential system notifications to be sent, while \u2018No access\u2019 halts all outbound emails, providing a safe environment for testing or when email communication needs to be paused temporarily.<\/p>\n<h2>Utilizing email warm up tools to prevent SMTP errors<\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"Graph showing email warmup performance with a line chart which helps with email sender reputation score. The x-axis represents dates from June 1 to June 9, and the y-axis represents email volume. Two lines indicate sent (1,200) and received (1,100) emails. Background is a soft gradient.\" height=\"600\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/03\/11092911\/8shots_so-1.webp\" width=\"800\" title=\"\"><\/p>\n<p>SMTP Email Error 552 5.7.0 can have a real impact on your email communication, mostly in regards to deliverability and server trust. Luckily, you can use a tool like <a href=\"https:\/\/www.warmy.io\/\" target=\"_blank\" rel=\"noopener noreferrer\">Warmy<\/a> to prevent and solve it before it even happens:<\/p>\n<ul>\n<li>Warmy focuses on improving email deliverability by slowly raising the number of emails sent from your account, so you build a reputation with ISPs as a trusted sender.<\/li>\n<li>Warmy also offers additional tools that let you check whether your email is likely to get delivered and give you some feedback on what problems you could expect.<\/li>\n<li>One of the more critical options is checking your blacklist status. Being blacklisted is a big problem since it almost kills your ability to send emails from your own server.<\/li>\n<li>Warmy also streams your ability to manage email authorization records, and it provides free <a href=\"https:\/\/www.warmy.io\/free-tools\/spf-generator\" target=\"_blank\" rel=\"noopener noreferrer\">SPF<\/a><span> and <\/span><a href=\"https:\/\/www.warmy.io\/free-tools\/dmarc-generator\" target=\"_blank\" rel=\"noopener noreferrer\">DMARC<\/a><span> records generators for you. SPF and DMARC records are vital for proving your emails are not a scam and have not been tampered with in transit. You can use properly set up SPF and DMARC records to be more resilient to SMTP Email Error 552 5.7.0 and protecting your domain from being used for email spoofing.<\/span><\/li>\n<\/ul>\n<h3>Test your deliverability before you hit send<\/h3>\n<p>Before launching a major email campaign, it\u2019s essential to know where your emails are landing.<\/p>\n<p>Are they reaching the inbox, getting filtered into the promotions tab, or worse\u2014ending up in spam? With <a href=\"https:\/\/www.warmy.io\/free-tools\/email-deliverability-test\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>Warmy\u2019s Free Deliverability Test<\/strong><\/a>, you can check inbox placement across multiple providers and address any issues early\u2014whether it\u2019s related to your SPF, DKIM, DMARC setup, timing, or content.<\/p>\n<p>Complementing this is the <strong>Domain Health Hub<\/strong>\u2014a comprehensive dashboard that provides deep insights into your domain\u2019s performance, including:<\/p>\n<ul>\n<li>\n<p>A domain health score based on authentication, blacklist status, and inbox placement<\/p>\n<\/li>\n<li>\n<p>Weekly and monthly reports to help you track spam rates and deliverability trends<\/p>\n<\/li>\n<li>\n<p>DNS checks to verify SPF, DKIM, and DMARC records<\/p>\n<\/li>\n<li>\n<p>Multi-domain monitoring for businesses managing multiple email domains<\/p>\n<\/li>\n<\/ul>\n<p>The <a href=\"https:\/\/www.warmy.io\/free-tools\/template-checker\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>Template Checker<\/strong><\/a> goes a step further by scanning your subject lines, email body, formatting, and links to identify any elements that might trigger spam filters\u2014especially within UK-based ISPs. You\u2019ll receive practical, actionable suggestions to refine your tone, remove problematic language, and improve overall structure. Now available as a convenient <a href=\"https:\/\/chromewebstore.google.com\/detail\/email-template-checker-wa\/oelldnebggajjfacfajacfbkeekeakip\" rel=\"noopener\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>Chrome Extension<\/strong><\/a> for quick content checks.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"A user interface displays an email template focused on improving deliverability, with subject and message fields on the left and template analysis on the right, showing stats like subject length, word count, and personalization score.\" height=\"600\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/05\/15090244\/template-checker-1.webp\" width=\"800\" title=\"\"><\/p>\n<h3>AI-powered warm up with customization<\/h3>\n<p>Warmy.io simplifies the email warmup process by leveraging advanced AI to simulate natural sending behavior. This helps gradually build a strong sender reputation\u2014without the need for manual intervention.<\/p>\n<p>With the introduction of the <strong>Warmup Preferences<\/strong> feature, users can now customize their warmup strategy by email provider. This allows for a more strategic distribution of email volume across multiple ISPs, ensuring alignment with provider-specific thresholds and improving overall inbox placement.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" alt=\"A dashboard displaying a profile section with a circular chart titled WARM-UP PREFERENCES. The chart shows percentages for Gmail, Outlook, G-Suite, Yahoo, and others. A table beneath lists specific percentages and email services.\" height=\"600\" src=\"https:\/\/warmy-blog-wordpress-bucket.s3.amazonaws.com\/wp-content\/uploads\/2025\/03\/11092845\/290shots_so-copy-1-1024x768.png\" width=\"800\" title=\"\"><\/p>\n<p>Resolving and alleviating error responses such as SMTP Email Error 552 5.7.0 error is critical in achieving reliable delivery of emails.<\/p>\n<p>Regular review and updating of the email system should always be a priority to operate within the server\u2019s regulations. Managing your email settings allows you to take charge of your communication with your clients and avoid any form of a breakdown. The action is not only helpful in avoiding potential errors, but it also assists you in increasing email productivity.<\/p>\n<p>If you\u2019re serious about taking your email deliverability to the next level, <a href=\"https:\/\/www.warmy.io\/signup\" target=\"_blank\" rel=\"noopener noreferrer\">sign up with Warmy today.<\/a><\/p>\n<p>\ud83d\udcdc <strong>Related article<\/strong>:<\/p>\n<ul>\n<li><span><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-552-solved\/\" rel=\"noopener\" target=\"_blank\">SMTP Email Error 552 \u2013 How to Resolve [SOLVED]<\/a><\/span><\/li>\n<li><span><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-552-5-3-4-solved\/\" rel=\"noopener\" target=\"_blank\">SMTP Email Error 552 5.3.4 \u2013 How to Resolve [SOLVED]<\/a><\/span><\/li>\n<li><span><a href=\"https:\/\/www.warmy.io\/blog\/how-to-fix-smtp-email-error-552-5-1-1-solved\/\" rel=\"noopener\" target=\"_blank\">SMTP Email Error 552 5.1.1 \u2013 How to Resolve [SOLVED]<\/a><\/span><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Simple Mail Transfer Protocol is an essential part of email communication. Once an email is written and sent, the SMTP server is responsible for forwarding and ensuring its secure reception. So when SMTP errors occur, it hinders the effective sending and receiving of emails. The SMTP Email Error 552 5.7.0 is a message rejection due [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":4645,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[104],"tags":[],"class_list":["post-3866","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-email-deliverability"],"acf":[],"lang":"en","translations":{"en":3866},"pll_sync_post":[],"_links":{"self":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3866","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=3866"}],"version-history":[{"count":1,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3866\/revisions"}],"predecessor-version":[{"id":5679,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/posts\/3866\/revisions\/5679"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/media\/4645"}],"wp:attachment":[{"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/media?parent=3866"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/categories?post=3866"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.warmy.io\/blog\/wp-json\/wp\/v2\/tags?post=3866"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}