Arnold,
I am surprised you don't have problems sending to AOL as well.
They don't accept email from servers that do not have reverse addresses.
I don't accept email from severs without reverse addressing.
Mike Walter, MCP
3z.net a PCD Company
<http://www.3z.net>
"When Success is the Only Solution t h i n K 3z.net"
Mike,
Does it have an A RR?
Anyway... it's a heuristic which definately does give false positives.
The only requirement is that IF a domain/host accepts mail there MUST be
a postmaster@ address.
Regards,
Daniel
yes, and that's what's wacky. there is no requirement in the RFCs that
i'm aware of that mail senders have MX records pointing back at them.
there's not even a requirement for MX records for a domain, the SMTP
RFCs clearly indicate that in the absense of an MX record, an A record
will suffice.
for that matter, if i were running a very very large mail farm with high
volume in one or both directions, separating the inbound mail handlers
(MX hosts) from the outbound mail relays would be something that i'd
seriously consider doing as part of the architecture. this would interact
very badly with the mail rejection strategy outlined in the original post
in this thread.
richard
I am surprised you don't have problems sending to AOL as well.
They don't accept email from servers that do not have reverse addresses.
I don't accept email from severs without reverse addressing.of course this server does have a reverse mapping. But this reverse
mapped doamin does not have an MX record.Does it have an A RR?
It also does have an A RR. And the forward mapping does also match the
IP address.
Anyway... it's a heuristic which definately does give false positives.
The only requirement is that IF a domain/host accepts mail there MUST be
a postmaster@ address.
In this case the host *sends* mail ...
Arnold
If you squint and cross your eyes, you can even convince yourself that RFC2821
says it's OK for said address to be bouncing due to over-quota conditions,
because the requirement is for existence, not for usability. 
>>of course this server does have a reverse mapping. But this reverse
>>mapped doamin does not have an MX record.
>
> Does it have an A RR?It also does have an A RR. And the forward mapping does also match the
IP address.
OK, so the check is even broken in what it probably tries to verify...
that the reverse-domain of the sender IP would (possibly) be able to
receive mail (bounces).
> Anyway... it's a heuristic which definately does give false positives.
> The only requirement is that IF a domain/host accepts mail there MUST be
> a postmaster@ address.In this case the host *sends* mail ...
Sure. I was discussing the requirements for domains regarding email.
In this specific case, "domain" being the domain of the PTR of the
sending MTA host.
Regards,
Daniel
While I think it's pretty anal-retentive to require a mail sender to have a valid MX record, I don't see what would be so hard about setting up MX records for this scenario:
inbound-mx01 IN A 192.168.1.98
inbound-mx02 IN A 192.168.1.99
outbound-01 IN A 192.168.1.100
IN MX 10 inbound-mx01
IN MX 20 inbound-mx02
Or am I missing something?
-J
> for that matter, if i were running a very very large mail farm with high
> volume in one or both directions, separating the inbound mail handlers
> (MX hosts) from the outbound mail relays would be something that i'd
> seriously consider doing as part of the architecture. this would interact
> very badly with the mail rejection strategy outlined in the original post
> in this thread.
While I think it's pretty anal-retentive to require a mail sender to have a
valid MX record, I don't see what would be so hard about setting up MX
records for this scenario:
<snip>
Or am I missing something?
yes.
what's hard about it is getting every single mail server on the public
internet to suddenly be set up this way so that they can talk to one
single mail server with a "novel" policy.
ain't going to happen. false positive city.
cheers,
richard
> >>of course this server does have a reverse mapping. But this reverse
> >>mapped doamin does not have an MX record.
> >
> > Does it have an A RR?
>
> It also does have an A RR. And the forward mapping does also match the
> IP address.OK, so the check is even broken in what it probably tries to verify...
that the reverse-domain of the sender IP would (possibly) be able to
receive mail (bounces).
Why would bounces go to an outbound mail server? They go to the
envelope sender, which might well be in a different domain. The check
is simply ill-advised and will cause the system running such a check
to have cut itself off from a large number of legitimate sources of email
> > Anyway... it's a heuristic which definately does give false positives.
> > The only requirement is that IF a domain/host accepts mail there MUST be
> > a postmaster@ address.
>
> In this case the host *sends* mail ...Sure. I was discussing the requirements for domains regarding email.
In this specific case, "domain" being the domain of the PTR of the
sending MTA host.
If you are sending mail via a virtual ISP, then the 'real' ISP's mail
servers will probably be in a different domain than your virtual ISP
which might be a different domain than your account. Checking mail
reachability of an outbound MTA is simply absurd.