[Cialug] Qwest subtly filtering port 25

[Tim Perdue]

On 5/27/2011 4:51 PM, Tom Pohl wrote:
> Is it your server that you are sending to on the other side?
>
> I ask because if they are filtering based upon a RBL like spamhaus.org's zen list, the mail server might be rejecting the connection because of a rule that qwest designated like spamhaus' PBL (Policy Block List):
> http://www.spamhaus.org/pbl/
>
> You can remove your own qwest ip from such a list directly from spamhaus at the above URL.  Since you can telnet to port 25, that's why I think it may be PBL related because mail servers such as Qmail (toaster variety) will allow the connection, but drop you once you try to send mail through it.

It's my server and my client - Qwest is doing some sort of filtering - I 
as I mentioned, I just called tech support and they dropped the 
filtering and it works fine now.

This article is how I found out about it:

http://mikedopp.com/2011/bold-move-from-qwest-to-block-port-25-traffic/