What settings should my email server be mindful of to avoid bounce back from major email providers?
Yep, Windows Live can be a pain. 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)