nanog mailing list archives

Re: Outgoing SMTP Servers


From: Jeroen van Aart <jeroen () mompl net>
Date: Tue, 25 Oct 2011 17:28:13 -0700

Owen DeLong wrote:
It's both unacceptable in my opinion and common. There are even those
misguided souls that will tell you it is best practice, though general agreement,
even among them seems to be that only 25/tcp should be blocked and that
465 and 587 should not be blocked.

From my consumer POV.

If you get a static IP with your provider, whether it is home internet or co-location, there should not be anything blocked. You're paying extra for the static IP in the case of home internet and the least you can expect is no blocking. Otherwise what's the point?

You can always block/cancel later in case of abuse obviously.

Of course this (and the below) does not apply in case of dynamically assigned IPs to a pool of home internet users.

Best practice is to do what works and block as much SPAM as possible without
destroying the internet in the process. There are those who argue that blocking
25/tcp does not destroy the internet. By and large, they are the same ones who
believe NAT was good for us.

There shouldn't be any spam filtering or blocking on a static IP at the ISP level. The ISP should limit itself to filtering at their own mail servers.

Greetings,
Jeroen

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