Historically we have used out ISPs SMTP server to send mail. Our setup is such that incoming mail to us (our domain xxx.com) goes to message labs for scanning then hits our POP box. We use ExchangePop3 to download fromt he POP account and pump it into Exchange 2k3. This I like as it means I don’t have to open up the SMTP port on our firewall to allow mail in directly.
We ued to send out mail out (again via ExchangePop3) to Star Internets SMTP servers and with them we rarely had any issue swith outbound mail. We are now using an NTL:Telewest leased line so are now using their SMTP servers. They are unreliable and have a 10MB cap on message sizes so I changed our outbound setup to allow exchange to send mail out directly itself to recipients.
The issue we have with sending mail directly from our Exchange server is ANY email to the NHS (and we are a healthcare compnay who’s biggest customer is the NHS) gets bounced. Here is the bounce message:-
************************************************
From: postmaster@sidhil.com [mailto:postmaster@xxx.com]
Sent: 25 February 2009 17:54
To: Clive Siddall
Subject: Message Not Delivered
———————————————————–
Attention: Non-Delivery Report
———————————————————–
This report is generated by the email server at:
xxx.com
The message with subject:
“RE: Doherty stuff !”
and attached to this report was not delivered to the following
recipients:
Address: Sue.Rosborough@GP-B84007.nhs.uk
Reason: 503 Need RCPT (recipient) (503)
————–
************************************************
The only reason I can imagine this is happening is that the NHS server do a reverse lookup on the IP the mail came from (i.e. 62.250.160.81) which is ouut default outgoing public IP. This will reverse lookup to a DNS registry I had created of mail2.xxx.com. However if it is looking for the mx record for sidhil.com this is in fact 62.231.131.243 (a Star Internet IP) as our inbound mail goes through that route.
What could possible be goiing wrong here????
Cheers
David