I inhertied this network recently and all the sudden i'm getting emails not delivered to some domains " the connection dropped by the remote host"
When i use mxtoolbox.com to check my company SMTP diag, it shows the message below
Not an open relay.
0 seconds - Good on Connection time
0.250 seconds - Good on Transaction time
OK - 65.xxx.xxx.98 resolves to
Warning - Reverse DNS does not match SMTP Banner
250 server.domain.com Hello [64.xxx.xxx.133] [62 ms]
MAIL FROM: <firstname.lastname@example.org>
250 2.1.0 email@example.com...
.Sender OK [62 ms]
RCPT TO: <firstname.lastname@example.org>
550 5.7.1 Unable to relay for email@example.com [62 ms]
221 2.0.0 server.domain.com Service closing transmission channel [62 ms]
I read the blog http://demazter.wordpress.com/2010/02/09/exchange-dns-configuration/
and i actually changed my fqdn to mail.domain.org and also created an A record that matched that and an mx record but i still got the same error and the emails dont go from any host in my network. an example of the domain i cant send to is vnab.org
I have 2 domains domain.org and domain2.com but all our emails are @domain.org however all the A hosts are configiured under domain2.com
Please advice me on what to do.
if necessary i can upload an image of the dns in my server if that is not dangerous to my network