What does the email error '552 5.2.0 sender rejected AUP#POL' mean and how to resolve it?

Marketer from Email Geeks reveals the issue was related to the age of the domain seen in the PTR record for the sending IPs. The domain was new and registered via a provider favored by spammers.

Email marketer from StackOverflow shares that resolving 552 errors typically involves ensuring that your sending domain has proper authentication (SPF, DKIM, DMARC), maintaining a good sender reputation, and adhering to email sending best practices to avoid being flagged as spam. Also, they suggest contacting the recipient server administrator for specifics.

Email marketer from Super User forum suggests that the 'AUP#POL' portion of the error message likely refers to a specific policy violation set by the recipient's email provider. To fix this, identify the email provider responsible for the bounce, consult their AUP documentation, and adjust your sending practices to comply with their policies.

Email marketer from Reddit user u/EmailHelpNeeded shares that 'sender rejected' errors can occur if the sending server's IP address has been flagged as a source of spam. Recommends checking blacklists, reviewing email sending practices, and contacting the recipient's email provider to request delisting.

Email marketer from Mailjet explains that 5xx SMTP errors are permanent failure errors, meaning the email could not be delivered and should not be retried. They explain that this class of error typically means a problem at the senders end. Specific error messages like AUP#POL would point to the receiving server's policy restrictions.

Email marketer from Gmass.co explains that 552 bounce codes may be triggered if your email content contains suspicious keywords or phrases that flag spam filters. They suggest reviewing your email content, avoiding spam trigger words, and personalizing your messages to reduce the likelihood of being flagged.

Email marketer from EmailOversight.com explains that a 552 error code alongside a policy restriction indicates that your sending IP or domain has triggered a filter on the receiving server (e.g. Cox). Resolution involves checking your sender reputation, ensuring your email practices align with best practices, and contacting the recipient's provider to understand their specific filtering rules.

Expert from Word to the Wise responds by explaining that while the exact meaning of 'AUP#POL' can vary, the 552 error points to the sender failing a policy check. They would start by checking the sender's IP and domain reputation against common blacklists, ensuring proper authentication (SPF, DKIM, DMARC) is configured, and then contacting the recipient's ISP to understand the specific policy being violated.

Expert from Email Geeks shares that the servers causing the rejection are run by Cloudmark, operating under the banner of cloudfilter.net, even if the IPs are in AWS.

Expert from Email Geeks advises to always check the banner of the email server for identification purposes, providing an example of how to connect to a mail server and view its banner.

Expert from Email Geeks explains that the 'Sender rejected' error is specific to the sender and indicates a problem with the sending platform's reputation rather than the recipient.

Expert from Spam Resource explains that the AUP (Acceptable Use Policy) component of the error indicates a violation of the recipient ISP's policies. They would recommend carefully review the specific ISP's AUP to identify the violation, which may include issues such as sending unsolicited emails, exceeding sending limits, or having poor list hygiene.

Documentation from Microsoft Learn explains that SMTP 5xx errors are permanent failure codes. While it does not explicitly address 'AUP#POL', the documentation points to the general class of 5.2.0 errors meaning that the mail server encountered a permanent error, but it doesn't know enough to be more specific about the error. Further investigation of the specific error from the recipient's mail server administrator is needed.

Documentation from DigitalOcean.com provides general guidance on diagnosing email bounce issues, advising to check SPF, DKIM, and DMARC records to ensure proper email authentication. Additionally, it suggests verifying the sender's IP address isn't blacklisted and to ensure compliance with the recipient's email provider's policies.

Documentation from Cox.com explains that a 552 error code generally indicates a problem with the sender's email or sending practices, leading to the rejection of the email. The AUP#POL often refers to a violation of Cox's Acceptable Use Policy. To resolve this, review Cox's AUP, ensure your email practices comply, and contact Cox support for specific guidance on the AUP#POL code.

Documentation from RFC Editor specifies enhanced mail system status codes. While it does not have a specific example for AUP#POL, it does explain that 5.2.0 indicates that a destination mailbox has refused to accept a message for policy reasons.