Port 25 filters - how many here deploy them bidirectionally?

Christopher L. Morrow christopher.morrow at mci.com
Sun Jan 9 16:25:43 UTC 2005

On Sun, 9 Jan 2005, Suresh Ramasubramanian wrote:

> .. and if it has been tried, have you noticed any issues with this?
> Please consider the situation of net abuse with the source address
> being an infected PCs on a dialup pool that has port 25 filtering
> enabled.

...description of 'fantasy mail' removed...

> So, a quick poll .. how many ISPs here have noticed this behavior, and
> applied bidirectional filters?  And if they've applied port 25 filters
> bidirectionally, have they noticed any problems with this setup?

I believe reseller contracts have included this for over 2 years now, John
StClair's efforts to get these in place are the primary reason they exist
for our customers.

> This ISP's post is only the second I've seen noting such behavior in a
> few months, the first being a nanog post in Aug 2004 by Hank
> Nussbacher - http://www.cctec.com/maillists/nanog/current/msg03171.html

We'd first seen this behaviour over 2 years ago... quite a bit actually
over that time as the filters had been put into place.


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