I had noticed recently that I was sending emails to certain people and not receiving replies (when it could be expected I’d get some). Well, it appears that some hostings services are starting to tightly conform to RFC 2181 by the IETF (Internet Engineering Task Force), which was updated in July of 2009.
What’s happening is basically that mails sent by the mail servers that are set up with aliases for the domain are getting bounced by these hosts that are conforming to RFC 2181. The servers should be set to a proper A record or directly to an IP address to prevent this issue. If you’re having similar issues, talk to your hosting company (if your mails are bouncing) or talk to the people who sent the emails whose emails bounced when they sent them to you.
For me personally, I know I need to keep my emails in check since it’s a primary form of communication and business, so this is rather important. It’s good to be aware of such updates that can have an impact on potential business and even on personal communication.