[Cialug] Qwest subtly filtering port 25

[Tom Pohl]

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.

Thanks!
-Tom


On May 27, 2011, at 4:18 PM, Tim Perdue wrote:

> Not sure if anyone else ran into this, but it had me vexed all week. I have used thunderbird for years from home to relay off an outside server and it just quit working and starting giving an error about SMTP timeout.
> 
> Turns out Qwest has done some sort of subtle blocking of port 25 that causes SMTP to timeout, although the port appears to be open (you can telnet to it).
> 
> http://mikedopp.com/2011/bold-move-from-qwest-to-block-port-25-traffic/
> 
> A call to tech support got them to drop the filtering within a few minutes and my email works again.
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