What are the best practices to configure a mail server to have your mail recognized as legitimate non spam messages? Is it to use Domain Keys, Sender ID, Sender Policy Framework, some or all 3 of these together?
3 Answers
There are a few similar mail related questions on SF already, however I'll answer this one as best I can. To avoid being recognised as spam, check:
- You're not on a blacklist
- Your server has MX and reverse DNS records
- You have SPF DNS records (many servers reject mail without a valid SPF, GMail for example, here's an explanation and a wizard)
- Your mailserver's HELO response matches your hostname
- Your mailserver is not an open relay
- Your DNS records' TTL is not too low - 86400 (24 hours) is recommended (some spammers set their TTL very low to regularly update forged DNS records)
I have never required Sender ID, although as it's a Microsoft protocol I'd assume it's more important for Exchange/Live based mail - I have never had problems in this department without implementing Sender ID.
-
This was exactly the type of answer I was looking for, thanks Andy! Oct 8, 2009 at 21:36
I've found that disabling open SMTP relay, and having valid reverse DNS entries, is a good starting point.