How to resolve Comcast Xfinity 552 5.2.0 email rejection policy error?
Michael Ko
Co-founder & CEO, Suped
Published 19 Apr 2025
Updated 18 Aug 2025
8 min read
Receiving a 552 5.2.0 Prohibited by policy email rejection from Comcast Xfinity can be incredibly frustrating. This error indicates that your email, while successfully delivered to the Comcast mail servers, was rejected due to a policy violation. It is not necessarily an IP block, which can sometimes complicate troubleshooting if you're primarily focused on that. I've seen many senders encounter this, especially when dealing with Comcast's specific filtering rules, and it often points to issues beyond basic authentication.
This policy error can stem from various factors, including the content of your message, the size of attachments, or even subtle aspects of your sender reputation that are not always immediately obvious. Unlike some other ISPs, Comcast (Xfinity) maintains a robust set of internal policies to combat spam and abuse, which means a generic 552 5.2.0 error needs a deeper investigation to pinpoint the exact cause. My goal here is to help you understand what might be happening and outline a systematic approach to resolving these rejections.
The 552 5.2.0 error from Comcast Xfinity's mail servers typically means the message was rejected because it violated one of their internal policies. This isn't a temporary issue; it's a hard bounce, signaling a permanent rejection of that specific email. While the error message itself is quite general, the additional text, such as 'Prohibited by policy,' gives us a strong hint that the problem lies with how Comcast perceives the email or the sending domain.
I've observed that this rejection can occur for several reasons, and it is crucial to analyze the full bounce message for any additional clues, such as specific tracking IDs or references to a particular policy. Sometimes, the issue is related to the overall sender reputation or adherence to email authentication standards. Other times, it's about the message content or size, which are often overlooked when troubleshooting.
Understanding the specific context of your emails (e.g., transactional, marketing, personal) and the volume you're sending to Comcast recipients can help narrow down the potential causes. For instance, a policy violation for a single, large attachment might be different from a policy violation for a high volume of marketing emails with certain keywords or links.
This error can often be confused with other bounce codes like general 552 errors or Gmail's 552 5.7.0 rejections, but the 5.2.0 subtype combined with Prohibited by policy points specifically to Comcast's filtering. If you're experiencing a 552 5.2.0 sender rejected AUP#POL error, the sender rejected AUP part suggests an Acceptable Use Policy violation, which ties directly into content and behavior policies. This distinction is important for targeted troubleshooting.
Sender authentication and reputation
Even if your SPF, DKIM, and DMARC records appear to be correctly set up and passing, as the slack post indicates, Comcast may still flag emails for policy violations. While authentication is foundational for deliverability, it doesn't guarantee inbox placement if other policy filters are triggered. I've often seen situations where a passing DMARC record still results in rejection due to reputation issues or content flags.
Sender reputation: Even if not on a public blacklist, your IP or domain might have a low reputation score with Comcast's internal systems. This can be due to historical sending patterns, complaints, or if you're sending from a new IP that hasn't established trust. I always recommend monitoring your domain reputation closely.
Content analysis: Comcast, like other ISPs, uses sophisticated spam filters that analyze email content, including keywords, links, image-to-text ratio, and even the email's structure. If your email resembles common spam patterns, it can trigger a policy block. This is especially true if you're sending bulk emails.
Attachment policies: Some 552 errors are specifically related to attachment size or file type. If your attachment exceeds Comcast's size limits (often 10-25MB, depending on the server), or if the file type is deemed suspicious, it will be rejected.
Forwarding issues: If an email is being forwarded to a Comcast account, DMARC policy can sometimes cause rejections. This is because the forwarding server might break SPF or DKIM alignment.
Even with perfect authentication, Comcast can still block emails due to sender reputation. This is why I advise all my clients to not only ensure their authentication is correct but also to actively manage their sending behavior and monitor for any signs of declining reputation. A domain on a blacklist (or blocklist) is a clear indicator, but internal reputation systems can be more subtle.
Ensuring proper authentication
SPF record: Verify that your SPF record includes all IP addresses or sending services authorized to send emails on behalf of your domain. Improper SPF setup can lead to rejections, even if not explicitly cited in the bounce message. For example, some ESPs might use a p=reject policy that causes immediate rejections.
DKIM signature: Check that your emails are consistently signed with a valid DKIM signature. A missing or invalid signature can reduce trust signals with ISPs like Google and Comcast. DKIM temporary errors can also indicate issues.
DMARC policy: Ensure your DMARC record is correctly configured and aligned. A strict DMARC policy (p=reject) with alignment issues can lead to rejections. You can use a free DMARC record generator to create one. Regularly reviewing your DMARC reports can reveal authentication failures.
Content and attachment policies
Comcast's spam filters are highly sensitive to email content. I've often seen emails rejected due to certain keywords, suspicious links, or an overall high spam score. This is particularly true for marketing or bulk emails. Reviewing your email content for anything that might trigger a spam filter is a critical step.
Spam triggers: Avoid excessive capitalization, exclamation marks, suspicious phrases, or links to questionable domains. I always recommend plain text versions of your emails too, as a backup.
Attachment size: If your email includes an attachment, check its size. Comcast has limits, and exceeding them will result in a 552 error. For larger files, consider using cloud storage and sharing a link instead. Also, certain file types (.exe, .zip, etc.) might be blocked regardless of size.
HTML vs. plain text: While HTML emails are common, overly complex or poorly coded HTML can sometimes trigger filters. Ensure your HTML is clean and simple. Including a plain text alternative is always a good practice.
I've helped clients resolve this by simplifying email templates, removing unnecessary tracking pixels, and ensuring that any links within the email point to reputable, unblocked domains. Sometimes, a subtle change in phrasing or a reduction in image-to-text ratio can make a significant difference. Remember, the goal is to make your email look as legitimate and non-spammy as possible to Comcast's filters.
Troubleshooting and resolution steps
When facing a persistent 552 5.2.0 error, a systematic troubleshooting approach is essential. I always advise starting with the simplest checks and then moving to more complex investigations. The key is to gather as much information as possible from the bounce message itself and then compare it with your sending practices.
Troubleshooting steps
Review bounce message: Look for specific policy IDs or additional text that might offer clues. Sometimes Comcast includes a URL to their postmaster site or a specific error code like AUP#POL.
Check content and attachments: Send a very simple, plain text email with no links or attachments to the Comcast recipient. If that delivers, start adding elements back in one by one to identify the trigger. This is a crucial diagnostic step.
Monitor blocklists (blacklists): While the error doesn't explicitly state an IP block, it's wise to check if your sending IP or domain is listed on major public blocklists. Comcast may use some of these, or have internal ones that mirror them. Suped offers a free blocklist checker.
Contact Comcast Postmaster: If you've exhausted other options, reaching out to Comcast's postmaster team is necessary. Provide them with the full bounce message, including headers, and any steps you've already taken. While they sometimes focus on IP reputation, I've found it helpful to clearly state that you suspect a domain or content policy issue.
Remember, the issue might not be global for all Comcast recipients, but specific to certain mailboxes or subdomains. This highlights the importance of asking the recipient to check their spam folder, and also if they have any specific rules set up that might be affecting your emails. Sometimes, the simplest solution is a whitelisting request from the recipient.
It can also be useful to perform an email deliverability test using an online tool. This can sometimes give you a clearer picture of how your email is perceived by various filters, including those similar to Comcast's. Such tools can identify issues like broken links, spammy content, or authentication misconfigurations that might lead to policy rejections.
Views from the trenches
Best practices
Maintain consistent email volume and avoid sudden spikes, which can trigger policy filters.
Regularly monitor your sending reputation and promptly address any signs of decline.
Ensure all email authentication records (SPF, DKIM, DMARC) are correctly configured and valid.
Segment your email lists and send targeted content to reduce spam complaints.
Provide clear unsubscribe options in all marketing emails to avoid user complaints.
Common pitfalls
Ignoring generic 552 5.2.0 errors and not investigating specific policy violations.
Focusing solely on IP reputation without considering domain reputation or content issues.
Sending emails with excessively large attachments or suspicious file types.
Using overly promotional language, spam trigger words, or too many images in emails.
Not contacting Comcast's postmaster with detailed bounce information and full headers.
Expert tips
If your client is 100% blocked, ask if they have been sending to cold or unengaged lists. Comcast is very strict with reputation.
Verify all links in your email are fully qualified (start with http/https) and are not to domains with poor reputations.
Check for any URL shorteners or redirects in your emails, as these are often flagged by policy filters.
Ensure your sending infrastructure's reverse DNS (rDNS) is correctly configured and resolves to your sending domain.
Consider a warming-up period for any new sending IP addresses or domains before sending high volumes to Comcast.
Marketer view
A marketer from Email Geeks says they had a client completely blocked by Comcast/Xfinity, receiving the 552 5.2.0 'Prohibited by policy' error, even though it wasn't an IP block and authentication was passing. They needed suggestions beyond just contacting Comcast postmaster.
2024-03-12 - Email Geeks
Expert view
An expert from Email Geeks suggests that the 5XX error might be more than 30 days old and asks for a newer one, indicating the importance of current bounce data for diagnosis.
2024-03-12 - Email Geeks
Key takeaways for reliable deliverability
Resolving a Comcast Xfinity 552 5.2.0 email rejection requires a holistic approach, looking beyond just IP blocks and basic authentication. By systematically examining your email content, attachment practices, and overall sender reputation, you can identify and address the underlying policy violations. It is a process of elimination and refinement.
Proactive monitoring and adherence to best practices are key to maintaining good deliverability with ISPs like Comcast. If initial troubleshooting doesn't yield results, don't hesitate to engage directly with their postmaster team, providing them with all the necessary details to help them investigate your specific case. Consistent effort in these areas will significantly improve your chances of reaching the inbox.
Google and Comcast. DKIM temporary errors can also indicate issues.
