How to resolve Comcast email rejections and throttling issues?
Summary
What email marketers say12Marketer opinions
Marketer from Email Geeks says that Vade is likely identifying messages from a shared IP as spam due to content/reputation. They recommend contacting Vade with IP, domain, and sample messages to understand and resolve the issue.
Email marketer from EmailFAQ shares that checking your IP address and domain reputation on blocklists is important. If you're listed, it can lead to rejections and throttling. They suggest using tools like MXToolbox or Talos to check your reputation and taking steps to get delisted if necessary.
Email marketer from Reddit shares that consistently sending engaging and valuable content, coupled with list hygiene practices like removing inactive subscribers, contributes to a positive sender reputation. Improved reputation can mitigate throttling and rejections.
Email marketer from Email Marketing Forum suggests monitoring your sender score using services like Sender Score. A low sender score indicates reputation issues that can lead to deliverability problems.
Email marketer from Email Service Blog shares that crafting high-quality, relevant, and engaging content can significantly improve email deliverability. Avoid spam trigger words and ensure your emails provide value to the recipient.
Email marketer from Quora answers that Regularly cleaning your email list by removing invalid, inactive, or unengaged subscribers will improve your sender reputation. Sending emails to recipients who don't want them can damage your deliverability.
Email marketer from Mailjet shares that if you're using a new IP address, gradually increasing your sending volume over time (IP warming) helps build a positive reputation with ISPs like Comcast. Sudden spikes in volume can trigger throttling.
Marketer from Email Geeks suggests that the system taking the email out of queue via rewriting it to a hard bounce if it doesn't deliver is a good thing. They advise resolving the underlying issue to prevent it from worsening.
Email marketer from Email Deliverability Forum suggests using a dedicated IP address instead of a shared IP to give you more control over your sending reputation. Shared IPs can be affected by the sending practices of other users.
Marketer from Email Geeks explains that the error message indicates throttling, not a block or reject. It's based on an internal reputation system, considering historical quantity and quality.
Email marketer from Email Marketing Tips Blog shares that respecting Comcast's sending rate limits helps you avoid throttling. If you're sending a large volume of emails, gradually increase your sending rate and monitor your deliverability.
Email marketer from Stack Overflow explains that setting up feedback loops with ISPs like Comcast allows you to receive reports about spam complaints. This enables you to identify and remove problematic subscribers from your list, improving your overall reputation.
What the experts say3Expert opinions
Expert from Word to the Wise emphasizes that proper email authentication (SPF, DKIM, DMARC) and maintaining a good sender reputation are crucial for avoiding rejections and throttling from Comcast. A poor reputation can trigger their filtering mechanisms.
Expert from Spam Resource explains that Comcast, like other major ISPs, employs aggressive filtering and throttling techniques to combat spam. Understanding their specific policies and adapting your sending practices accordingly is key to ensuring deliverability.
Expert from Email Geeks explains that the 554 5.4.7 [internal] error message is generated internally (likely by Momentum) as a graceful way to handle throttling, while the 421 4.1.0 message comes from Comcast.
What the documentation says5Technical articles
Documentation from DMARC.org explains that Implementing DMARC (Domain-based Message Authentication, Reporting & Conformance) policy to tell receiving mail systems what to do with messages that fail authentication checks. This prevents spoofing and phishing attempts using your domain, boosting your reputation.
Documentation from SPF-record.com explains that publishing an SPF (Sender Policy Framework) record which specifies which mail servers are authorized to send emails on behalf of your domain improves the deliverability. Comcast and other ISPs check the SPF record to verify legitimate senders.
Documentation from RFC Editor explains that understanding SMTP error codes, like those returned by Comcast, helps diagnose the specific reason for the rejection or throttling. Error codes provide valuable clues for troubleshooting.
Documentation from Comcast Postmaster explains that they provide guidelines and requirements for sending email to Comcast subscribers. Understanding their policies, especially regarding authentication, list management, and content, is crucial to avoid rejections and throttling.
Documentation from DKIM.org answers that implementing DKIM (DomainKeys Identified Mail) authentication helps verify the authenticity of your emails to ISPs. This reduces the likelihood of emails being flagged as spam or rejected.