[ale] Blacklisted mail server?

[alelist at cxdonline.com]

> 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?
>
This sounds like a problem I recently had with GoDaddy blocking e-mails
sent from my server to some of GoDaddy's customers. It seems that the ISPs
are starting to block all port 25 traffic to their servers except for
traffic coming from other ISPs.

The fix was to set my ISP's mail server as a smart host in my sendmail
config. and route my outgoing e-mail though my ISP's e-mail server.
GoDaddy will accept e-mail from my ISP.

Steve