What causes Comcast 'no mail servers could be reached' timeout issues and how are they resolved?
Summary
What email marketers say13Marketer opinions
Marketer from Email Geeks confirmed that those IPs are not backup MX records.
Marketer from Email Geeks shares they're seeing increases in timeouts, tens of thousands in the last hour.
Marketer from Email Geeks shares that the two servers where they see the timeouts are: 96.114.157.80 & 68.87.20.5.
Email marketer from Reddit answers that the 'no mail servers for domain could be reached' error could indicate a problem with Comcast's DNS servers, issues with the recipient's mail server, or a temporary routing problem. He recommends retrying the email later.
Email marketer from StackExchange responds that the error might stem from Comcast's outbound mail servers being temporarily blacklisted. He suggests checking blacklists using online tools to see if Comcast's IPs are listed.
Marketer from Email Geeks confirms seeing the same IPs from a query.
Marketer from Email Geeks shares that there were Comcast resolution issues late last night through the early hours of this morning, but Comcast confirmed they had issues with resolution ~7 hours ago so it should be better now though.
Marketer from Email Geeks shares that they think they've remediated the issue, just working on recovery.
Marketer from Email Geeks shares that the bounce response would likely be timeouts.
Email marketer from Experts Exchange explains the error could also indicate a firewall issue, where Comcast's firewall is blocking connections to the recipient's mail server. He recommends checking firewall logs.
Email marketer from SuperUser responds that the error might be due to the recipient's mail server being temporarily down for maintenance. She suggests trying again later or contacting the recipient directly.
Email marketer from Webhostingtalk shares a response on webhostingtalk.com, recommends contacting Comcast support directly, as they would have detailed insights into any outages or network issues affecting their email services and may be able to resolve the issue.
Email marketer from Quora responds that one cause may be incorrect DNS records or a DNS server outage. This could be a problem on the sending side (Comcast) or the receiving side (the target domain), and can also be due to firewall settings, especially if the target domain is self-hosted.
What the experts say2Expert opinions
Expert from Word to the Wise explains that bounce messages like 'no mail servers could be reached' can occur due to temporary DNS issues, server maintenance, or problems with the recipient's mail server. Retrying the email or contacting the recipient through an alternate method is advised.
Expert from SpamResource explains that issues often happen when email providers find you on a blocking list. If your email provider (Comcast in this case) gets blacklisted, emails can get blocked which would produce the type of error. They suggests checking common blocking lists to check if the sending server is listed.
What the documentation says5Technical articles
Documentation from Microsoft Learn explains that 'no mail servers for domain could be reached' often indicates transient DNS errors. These are often temporary and resolve automatically when DNS infrastructure corrects itself. The documentation suggests checking DNS server configuration and waiting for propagation after changes.
Documentation from Google Workspace Admin Toolbox explains one of the most common reasons is firewall settings. The firewall may be blocking the port that SMTP usually connects to. Checking the connection is necessary to find the root cause, which will help narrow down the next steps to resolve it.
Documentation from DigitalOcean explains that DNS propagation delays after DNS changes can cause temporary 'no mail servers' errors. They advise verifying DNS records and allowing ample time for changes to propagate globally.
Documentation from MXToolbox explains that their tools can be used to diagnose DNS and mail server issues. They advise using MX Lookup, DNS Lookup, and Blacklist Check tools to pinpoint the root cause of the 'no mail servers' error.
Documentation from Namecheap shares that if the records are not configured properly, it can lead to problems during email delivery. It is recommended to double-check and update the DNS records like A, MX, and TXT to fix the timeout issues. Using their tools is important to check and fix these issues.