Re:Port 25 will be blocked for South Korea from December
by mike-cardwell on Tuesday November 08, 2011 @07:57AM
(#3210530)
botnets are the source of the vast majority of spam. Not mail servers and not open relays. If a botnet program can make an outgoing port 25 connection, they can connect directly to the recipient mail server to send the spam.
Preventing them from making outgoing connections on port 25 means they have to connect to an intermediary server instead. Usually the ISPs. This makes it much easier to detect/block/rate limit them.
Most of the time however, they just give up when they can't make the outgoing port 25 connection. Or keep trying and failing.
Preventing them from making outgoing connections on port 25 means they have to connect to an intermediary server instead. Usually the ISPs. This makes it much easier to detect/block/rate limit them.
Most of the time however, they just give up when they can't make the outgoing port 25 connection. Or keep trying and failing.