Mail server cannot send email to a specific domain

[Jeffrey Meltzer]

When dealing with mail, the fwd/rev should always match.

Ie,

  yourdomain.com.	IN	MX	10 mail.yourupstream.com.
 
  mail.yourupstream.com.	IN	A	10.11.12.13

  13.12.11.10.in-addr.arpa.	IN	PTR	mail.yourupstream.com.

Is the normal, proper way to set things up. Having the mx pointing to
mail.yourdomain.com where mail.yourdomain.com is a cname to
mail.yourupstream.com is a nice way to pretend you have your own mailserver,
but it's broken.

Also, lots of spam checker's check to make sure fwd/rev dns matches.

jeff

> -----Original Message-----
> From: bind-users-bounce at isc.org 
> [mailto:bind-users-bounce at isc.org] On Behalf Of JRR
> Sent: Wednesday, September 24, 2003 11:17 AM
> To: comp-protocols-dns-bind at isc.org
> Subject: Mail server cannot send email to a specific domain
> 
> This may not be the place for this and I'm not a DNS pro (although I
> understand the concept and can setup simple DNS entries), but 
> I'm not sure
> if this is DNS related or not, so here goes...
> 
> I have a Windows based mail server that has a really tough 
> time forwarding
> emails to a particular domain that is hosted by a hosting 
> company.  The
> receiving domain hosting company assures me there are no 
> problems on their
> end, but I'm not so sure.  I am also unable to forward emails 
> to the hosting
> company themselves.  My mail server SMTP log shows timeouts 
> connecting to
> the receiving mail server.  Every now and then a message will 
> get through.
> Connectivity is not an issue.
> 
> I started checking things out and initially found the 
> receiving domain MX
> was referencing a CNAME entry.  They fixed this, but still no 
> go.  Then,
> there was no reverse DNS entry for the receiving MX.  They 
> fixed this too,
> but I have a question about this one.
> 
> I'm told by the mail server manufacturer that the reverse DNS 
> entry for the
> receiving domain MX should reference the mail server itself 
> or the exact
> problems I'm seeing can happen.  This is an example of how 
> the reverse DNS
> entries are setup for the subject domain:
> 
> Mail server manufacturer says it SHOULD look like this (which 
> is the way I
> usually see them):
> 
> x.x.x.x.in-addr.arpa mail.receivingdomain.com.
> 
> In the case of the subject domain, the reverse DNS entry 
> looks like this:
> 
> x.x.x.x.in-addr.arpa hostingcompanydomain.com.
> 
> 
>