E-mail issue

[phreak]

Hi there,

 

I have a strange problem whereby nobody in my e-mail domain can e-mail this one company in Poland. Every time we try we get this error

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

 

We can however receive e-mails from them ok. Now the lady on the other end has come back and said it's a problem with our server configuration and her IT team have said this is the problem HELO cant be localhost

 

Any ideas/thoughts on this one would be appreciated. First time this has ever happened.

[SneakyBeaky]

SMTP error 550 Is: Requested action not taken: mailbox unavailable (E.g., mailbox not found, no access)

Seems like the error is their end.

But it could be that your sending mailserver does not correctly identify itself.

To be RFC 2821 compliant, the system name your computer transmits in the EHLO/HELO handshake (this occurs when two systems are about to exchange mail with one another) must be identical to the DNS name of the IP address that your computer is currently attached to. For example, if the DNS name for the IP address your mail server is on says "mailserver2.bobsbox.com", then the EHLO handshake must state that exact name.

I don't know why this would only be a problem with that one recipent and not others.

Edited June 11, 2010 by SneakyBeaky

[gl3nnym]

Maybe their mailserver has a policy where it only accepts correctly configure names?

[phreak]

Ok. So where can I check the name it has in the EHLO/HELO handshake? I'm assuming that is what your suggesting I check right?

[PiqueABoo]

That is the point i.e. your mail server is saying: "HELO animal.ebl.local", whereas in a perfect world it would be, and for this target it needs to be, using a resolvable-anywhere FQDN.

 

Where depends on that missing critical information i.e. what mail server have you got?

 

PS: People that set their MTAs to do that kind of check tend to be irritating pedants. It's just not that useful in the spam wars.

 

PPS: I had to go check this was still the case, but RFCs are not official Internet standards until they're made part of an STD. RFC2821 might be a defacto standard, but out-pendanting-the-pedants it is still a PROPOSED STANDARD for Internet e-mail. [What I'm not sure about is whether the powers-that-be do the RFC -> STD stuff anymore]

Edited June 11, 2010 by PiqueABoo

[phreak]

Ahh yes, sorry. We are running Exchange server 2003 Enterprise on a Windows 2003 server SP2 system.

[PiqueABoo]

May or may not help or break something else, but you can change the FQDN it uses in HELO on the properties of the SMTP virtual server -> Select Delivery tab -> Advanced button.

[phreak]

Checked that and no difference.

 

Any other suggestions?