| Non-Specific Error Codes
|
| Error Code Returned |
Explanation |
| 421 - [Too many sessions opened] | Comcast allows 10 simultaneous connections. This error results when that limit is exceeded. |
| 421 - [Reverse DNS failure : Try again later] | Comcast requires all sending IP addresses have a valid rDNS. This error results when the lookup failed. This error should be treated as a temp- fail and can be retried. |
| 421 - [Try again later] | This error results for several reasons. This error should be treated as a temp-fail and can be retried. |
| 452 - [Too many emails sent on this session] | Comcast allows 1000 emails per session. This error results when that limit is exceeded. |
| 452 - [Too many recipients for message] | Comcast allows 1000 recipients per message. This error results when that limit is exceeded. |
| 550 - [Not our customer] | This error results when a message is sent to a non- existent Comcast customer. These errors should be treated as an "unsubscribe" by the sender, if a bulk mailer. |
| 550 - [Invalid sender domain] | Comcast requires that all sending IPs have a valid A or MX record. This error results when neither record can be found. |
| 550 - [<$(_toemail)> Account not available] | This error results when a message is sent to a Comcast account that is currently not available. |
| 552 - [Message size exceeded] | Comcast allows messages of 15MB or smaller. This error results when that limit is exceeded. |
| 554 - [Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement. For more information, refer to: http://www.comcast.net/help/faq/index.jsp?faq=SecurityMail_Policy18784] | Comcast requires all sending IP addresses have a valid rDNS. This error results when no entry is found.
http://www.comcast.net/help/faq/index.jsp?faq=SecurityMail_Policy18784 |