The receiving server rejected your email based on a content or security policy. This can be triggered by spam content, blacklisted URLs in the message body, attachment restrictions, or organizational security policies.
What Does Error 541 Mean?
SMTP code 541 indicates the message was rejected due to a policy violation on the receiving server. This is a content-based or policy-based rejection rather than an address or authentication issue. The receiving server's content filters, DLP (Data Loss Prevention) rules, or security policies have determined the message should not be delivered.
Common triggers include blacklisted URLs in the message body, executable attachments, specific keywords that match DLP rules, or content that matches spam patterns. This code is also used by some servers when they detect malware or phishing content in the message.
Common Causes
- Message content triggered spam filters
- URLs in the message are on content blacklists
- Attachment type is blocked by the recipient organization policy
- Content matches DLP (Data Loss Prevention) rules
- Message detected as containing malware or phishing content
How to Fix Error 541
- Review your email content for spammy language, excessive links, or suspicious patterns
- Check that URLs in your email are not blacklisted
- Remove or change attachment types to ones allowed by the recipient
- Ensure your message does not contain misleading or deceptive content
- Test your email content with a spam score checker before sending
Frequently Asked Questions
SMTP error 541 means the recipient's email server has rejected your message based on an anti-spam or security policy. This permanent error indicates your email was classified as spam, your sender reputation is poor, or your message violated the recipient server's content or authentication policies. It is commonly returned by providers like Zoho (541 5.7.1) and Microsoft 365 (5.4.1) when emails fail content scanning, lack SPF/DKIM authentication, or originate from a blacklisted IP address.
To fix a 541 policy rejection, first check your sender reputation by looking up your sending IP on blacklist checkers like MXToolbox, Spamhaus, and SORBS. Then verify that your domain has correctly configured SPF, DKIM, and DMARC records to authenticate your emails. Review your email content for spam triggers -- avoid excessive links, all-caps text, misleading subject lines, and suspicious attachments. If sending cold outreach to Office 365 recipients, ensure your third-party sending service's IPs are included in your SPF record.
Yes, you can request whitelisting, but it requires action from the recipient's side. Ask the recipient to add your email address or domain to their safe sender list, address book, or server-level whitelist. If the 541 block is at the organizational level (common with Microsoft 365 or Google Workspace), the recipient's IT administrator may need to add your domain to their allowed senders list or adjust their spam filter policy. On your side, improving your sender reputation through proper authentication and gradual warm-up of sending volume will help prevent future rejections.
Both are permanent (5xx) errors, but they differ in specificity. Error 550 is a general-purpose rejection code used for a wide range of issues including non-existent recipients, full mailboxes, and relay denials. Error 541 specifically indicates the message was rejected based on the recipient's anti-spam or content filtering policy -- meaning the recipient address is valid, but the server blocked the message because of its content, the sender's reputation, or authentication failures. A 541 error requires improving your sending practices rather than just correcting an address.
Cold emails frequently trigger 541 errors because recipient servers are specifically designed to block unsolicited messages from unrecognized senders. Your sending domain may have low reputation if it is new or has not been properly warmed up, your IP may be shared with other senders who have sent spam, and your email content may match spam patterns. To reduce 541 errors in cold outreach, warm up your domain gradually, authenticate with SPF/DKIM/DMARC, personalize your content, limit daily sending volume, and avoid spam-trigger words and excessive links.