ingress SMTP

Mark Foster blakjak at
Fri Sep 5 04:12:03 CDT 2008

On Fri, 5 Sep 2008, Mikael Abrahamsson wrote:

> On Fri, 5 Sep 2008, Simon Waters wrote:
>> If the ISP blocks port 25, then the ISP is taking responsibility for
>> delivering all email sent by a user, and they have to start applying rate
>> limits.
> MUAs should stop sending email via 25 and use 587 or equivalent instead. 
> There is little actual reason why someone should be able to send TCP/25 SMTP 
> email from a residential connection when most software support authenticated 
> TCP/587 submits.
> We don't allow most of our residential customer base to speak SMTP TCP/25 to 
> anywhere at all (and we have millions of them). Wish more ISPs would do the 
> same.

Probably fair enough, if you as an ISP can get away with enforcing this 
sort of policy then so much the better.

However relaying through your own ISPs 25/tcp should surely then make it 
relatively easy for noise to be tracked down and nailed at the source - by 
ISPs?  (Do [email protected] desks investigate spam these days?)

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