Mark wrote:
Jo wrote:
I setup mail servers all the time and I always make sure the
Mail server broadcast name, the 'A' record and the PTR all match,
IT IS JUST GOOD PRACTICE.
No, it's NOT good practice. Seriously. Without battering the point, it's
really perfectly legit for an MTA to use different HELO names (say, based
on hosting of virtual servers), whilst the IP address for that MTA has a
"fixed" PTR.
The statement you're replying to doesn't say anything about the HELO
string. It says the PTR and A records should match (and they SHOULD).
This doesn't bother virtual domains at all.
For example:
IP addr A.B.C.D might have a PTR return "virtdomains.domain.tld"
virtdomains should have an A record returning A.B.C.D (perhaps among
other IP addrs).
The virtual domains can also have A records that say A.B.C.D. That
works, and doesn't violate the "PTR and A records should match" guideline.
And, in any case, the HELO string can be anything. It can be
virtdomains.domain.tld, or it can be one of the virtual domains, and
nothing should be wrong. And it wont violate the "PTR and A records
should match" guideline. Technically, it can be garbage, and still be
ok. Whatever it is, it doesn't change the item you replied to.
And, for dynamic end hosts, this guideline still works.
The IP addr W.X.Y.Z might go to client-W-X-Y-Z.someisp.com
then client-W-X-Y-Z.someisp.com has A record pointing to W.X.Y.Z.
And, last, mail.domain.tld might also be an A record pointing to W.X.Y.Z.
That still doesn't violate "PTR and A records should match". The IP
address leads to a hostname whose A record leads back to the IP address.
All is good. And you can still mail to [EMAIL PROTECTED] and it
will work.
(but if they send email directly to me, instead of through their ISP, I
will reject them, because their customer oriented IP address shouldn't
be directly submitting email to my mail server)
