Problem from Comcast Network to The Planet

Steven Bellovin smb at cs.columbia.edu
Fri Mar 5 15:41:03 CST 2010


On Mar 5, 2010, at 4:33 PM, Zachary Frederick wrote:

> We have been having a problem emailing to a customer whose server is hosted by The Planet (http://www.theplanet.com/). Our mail server is hosted in-house on a comcast business connection.
> 
> IP address of our server is: 173.13.45.23
> 
> Customers mail server is: 69.93.203.243
> 
> I cannot telnet to port 25 on their server, and they cannot telnet to port 25 on ours.
> 
> If I try to connect to their mail server from a different network such as my home internet connection, I can connect.
> We do not do any firewalling that would block this in anyway. We were able to send and receive email to them when we used Qwest for our connection, before we switched to Comcast.
> 
> Comcast has said the problem is not on their end because it times out at The Planet.
> The Planet doesn't have much interest in speaking with me, because I'm not their customer.
> 
> Not sure what to do at this point.
> 
> Below is a traceroute:

If you have a suitable platform, try tcptraceroute and see where port 25 is blocked.



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