On Wed, Mar 23, 2011 at 15:34, Martin Muraguri <martinmur87@gmail.com> wrote:

Hi Everyone,

So I installed Exchange server yesterday and though i had done it all.

then i get this error for specific domains only...

priscilla.thesecretary@eaded.org on Wed, 23 Mar 2011 15:25:07 +0300

There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.

<mymajordomain.com #5.5.0 smtp;550-Verification failed for <martin@mymajordomain.com>>

So the basic set up is for smtp
Client W/s (Outlook, Thunderbird, )
Exchange Server (Domain - Mymajordomain.com {Smtp Record points to this servers ip address on my domain host on the net.})

Recepients server (Most likely doing a reverse dns lookup)

Receiving is a different setup but it works fine.

Au contraire, I think the server for eaded.org is doing what is called Sender Verification - which is evil, but necessary for controlling spam.
Because you have obfuscated out your real domain, I am not able to advise you better, except that you need to run a test against your Exchange to see if it accepts VRFY.

telnet the-ip-of-your-exchange-server 25
mail from: <>
rcpt to: martin@mymajordomain.com

If the above fails, then you have a problem. Sender verification using "callout" with the sender_address on the envelope is quite common these days.