[ale] Blacklisted mail server?

[Joe Steele]

On Friday, March 18, 2005 2:54 PM, Nathan J. Underwood wrote:
>
> A client of mine has recently started using Cbeyond as their ISP.  Since
> the cutover, they've had problems sending emails to random domains.
> After digging around a bit, I've found that they seem to be blacklisted.
>     The error messages that the users are getting were pretty generic,
> so I started digging further.  My first move was to ping the server
> reported as the primary MX for the recipient (got a response).  I then
> tried to telnet to the mail server (i.e. telnet mail.server.net 25), and
> got an immediate connection refused.  I then tried the same exercise
> from my ip (not blacklisted), and was able to connect.  They're not an
> open relay, and I've not been able to find any lists that their listed
> on.  Anyone got any suggestions on where to look next?

Just a guess:

I believe Cbeyond doesn't usually have reverse DNS set up for their 
IP addresses.  Could it be that some mail servers are refusing the 
connection because of this?  If so, then your client can probably 
report the problem to Cbeyond and have them set up reverse DNS for 
their IP(s).

--Joe