[Dshield] Port 2500

stephane nasdrovisky stephane.nasdrovisky at paradigmo.com
Sun Mar 20 10:14:42 GMT 2005

>>>Anyone come across anything of note on port 2500 recently?
>>There are some advises across the web advocating the use of this port 
>>for smtp (in order to avoid spam).
spam should be read mail relay.

>I am at a loss to understand how the port change does anything other
>than break smtp.
It basically brakes smtp, but your users may submit new mails using this 
new port as far as you tell them how to configure their mail reader. (I 
know it's stupid, authentication seems a better idea)

For real world smtp, anyway, you need port 25. Sometimes, port 25 only 
allows mails to your domain (no mail relay), while the other port allows 
mail relay.

Some providers also filter port 25, so that you have to use some 
alternatives if you want your users to be able to send mail (port 587 is 
almost official for this purpose)

Changing the port settings is a way to avoid mail relay for lazy admins.
If you change the port and are not listening at all to port 25, you'll 
not receive any spam (in fact, you'll not receive any mail at all)

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