Dear, Good afternoon.
When sending mail to external users or other domain I get an error message from the server domain.
I can help solve this problem.
Thank you.
Subject: Reverse DNS needs to be set up
The error is saying that the reverse DNS lookup for your mailserver failed. This is a lookup the recipient’s server does to be sure the name & IP of the sending server is “legitimate” by seeing if it matches what is in DNS. Be sure the server sending your messages has an MX record that matches the name/IP from which it is sending. If this MX was recently added, it can sometimes take a day or two for it to replicate out into the public.
Subject: http://www.dnsstuff.com/
Use this site to diag your email failures.It does a great job detailing any email problems with a particular email server.