I been playing with finding a way to reduce spam. I am debian user who has a ispconfig setup and noticed fail2ban has added some support for email but nothing to deal with "rejected: User unknown in local recipient table" messages Now I am not a expert. But one thing I know is security usualy causes lotsa problems when you try to go the extra mile. so I thought I would run it by some of you before I actualy sit down and start running it .. i will run it on one domain first to see if it makes a diffrence. I am unsure if it will effect email forwards though? anyones thoughts here is the filter I found on the net showing a 554 error from mail log here is what I am wanting to do with it is form it to block 550 errors and I could use some help so before I start losing mail and screw things up what do you think?! now I figure from my logs it looks like they try like 4-5 times.. how many ligit ones get through 4 5 mistakes and even if they do a delay is no big deal is it? not sure what I am talking about. then take a look at some of these from my mail.log these evil name harvesting bots eating up cpu time, memory and bandwidth. we can go on all day how bad spam is. ever little bit will helf x 10 fold So I am crying for some tips here!