Let me rephrase my question
when a user on a virtual domain domain2.com send an email via the server
host domain1.com, will  smtp identify itself as Domain1.com or Domain2.com?

I looked up this "Imail helo's as" in the u/g and kb, and couldn't find for sure (esp since it's an important point), but I think I remember an answer in this list from Ipswitch person that Imail helo's with the default/canonical hostname for a given IP.


does the answer depends on whether the user authenticated or not ?

I would say no. there's no correspondance. Imail SMTPD greets+authenticates, but it's IMail SMTP that sends. Imail doesn't change it's HELO hostame to match every outbound @sender.domain it sends. eg, what about users who send through IMail using a domain that is not even an Imail domain, real or virtual?


If the answer is Domain1.com, then the "from" [EMAIL PROTECTED], will be
different from the ehlo/smtp/PTR
Is that tested by some servers ?

Sure.


eg, to prevent common forgeries of the helo hostname using the domains of BigISP (yahoo, hotmail, etc), IMGate can do this logic:

if helo is /BigISP/, then PTR must be /BigISP/.

if sender.domain is /big ISP/, then PTR must be /BigISP/

if PTR is /BigISP/, then sender.domain must be /BigISP/

etc, etc.

can it be a problem ?

not in general.


As I said, the ptr/helo/smtp-greet hostname is identified with the physical machine and its IP address, independent of the (virtual) envelope sender/recipient domains the machine emits/receives.

There is no required correspondence between a domain's MX hostname and PTR of IP it resolves to.

somedomain.com MX 10 mx.whatever.com.

but somedomain.com is not involved in matchup of:

mx.whatever.com. A A.B.C.D

D.C.B.A.in-addr.arpa PTR mx.whatever.com.

And then the MTA at IP A.B.C.D :

SMTP-greets as mx.whatever.com

HELOs as mx.whatever.com


Len


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