If your not aware there have been a few attacks on 2 of our mail servers causing some outages. We have been working hard combat this attack and have found a solution that’s works very well at stopping the attack and also reducing over all spam by as much as 50%. It seem as if it may end up to be a win win for both sides. We have had a large amount of complaints about spam and the recent attacks made us put our heads together again and come up with away to solve the issue and now we have.
Every mail server in the world has a retry attempt to deliver mail, this is how you get mail if the mail server would be down for less then 24 hours and keeps you from losing mail that has not made it to the server.
So we are using the option as well to stop the attack and spam. I will explain it again, I wish I could just draw a picture here. lol
1.
joe@somedomain.com sends you an email.
2. That email goes to there mail server.
3. There mail server tries to send the email. ( if they have sent an email before then they will skip 4 )
4. Our mail server says please try again later.
5. There mail server tries again in 7.5 min. up to 30 min later it goes right in to your mail box and they get added to the greylist. ( grey list means they no longer have to try and resend again it will allow there mail to come right through the next time )
So now any emails from
joe@somedomain.com will go right to your email box after there first time. So what this does is stop a LOT of spam because spammers in general don't use mail servers that retry, it also stops this attack because they are trying to reconnect every 5 seconds and they get black listed.
This does not affect your out going mail at all and I do recommend every one to use 2525 on there side for sending mail it should connect a bit faster as it a different process running then the one running on port 25 and could be a tad bit more backed up if the attack increases but at this point it is under control.
The system is about as fool proof as you can get going by the mail RFC's and will cut server load and spam load by a TON. If all works out we may use this system network wide and should reduce your spam by at least 50% or more and help prevent attacks such as the one we were and are under still at this time.
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