Inside customers, we have not changed to force port 587 and authentication for email clients, but the topic has come up in discussions. This won't of course, stop spammers if they are hijacking the users local email client settings.
How best would you stop spammers hijacking local users email clients -Mike -----Original Message----- From: Claudio Lapidus [mailto:clapidus@gmail.com] Sent: Wednesday, April 21, 2010 9:49 AM To: nanog@nanog.org Subject: Mail Submission Protocol Hello all, At our ISP operation, we are seeing increasing levels of traffic in our outgoing MTA's, presumably due to spammers abusing some of our subscribers' accounts. In fact, we are seeing connections from IPs outside of our network as many as ten times of that from inside IPs. Probably all of our customers are travelling abroad and sending back a lot of postcards, but just in case... ;-) So we are considering ways to further filter this traffic. We are evaluating implementation of MSA through port 587. However, we never did this and would like to know of others more knowledgeable of their experiences. The question is what best practices and stories do you guys have to share in this regard. Also please let me know if you need additional detail. thanks in advance, cl.