Hi! On one of the mailservers I run I get really much spam (as some mail addresses are really widely known). I'm using the courier dns blacklist feature as the first line of defence. It blocks a lot of spam, but I've a resources problem with it.
The problem is that the spam seems to hit this server in waves which lead to more then 10 times the connection rate as normal. Almost all of the connections are blocked by the dns blacklist feature, but the connections are somehow not dropped at once. This leads to entries like Jul 18 09:57:12 mail courieresmtpd: 250 maximum active connections. and as courier seems to start a process per connection also in a high memory usage up to 1GB only for smtp. I've tried to optimise the config, but every time I scaled something up the spammers still hit the max. active connection limit. Normally traffic would work with the default max. active connections setting of 40. E.g. I reduced the timeout values, it helped, but the spammers still send more than I'm able to close. # cat /etc/courier/esmtptimeout 30 # cat /etc/courier/esmtptimeoutconnect 30 # cat /etc/courier/esmtptimeoutdata 3M # cat /etc/courier/esmtpdelay 10M How can I optimise the setup further or to I need to change the setup by adding a proxy with works like lighttpd does as webserver? I'm running following versions # dpkg -l | grep courier ii courier-authdaemon 0.60.1-1ubuntu2 Courier authentication daemon ii courier-authlib 0.60.1-1ubuntu2 Courier authentication library ii courier-authlib-userdb 0.60.1-1ubuntu2 userdb support for the Courier authenticatio ii courier-base 0.58.0.20080127-1ubuntu1 Courier mail server - base system ii courier-imap 4.3.0.20081027-1ubuntu1 Courier mail server - IMAP server ii courier-imap-ssl 4.3.0.20081027-1ubuntu1 Courier mail server - IMAP over SSL ii courier-maildrop 0.58.0.20080127-1ubuntu1 Courier mail server - mail delivery agent ii courier-mta 0.58.0.20080127-1ubuntu1 Courier mail server - ESMTP daemon ii courier-mta-ssl 0.58.0.20080127-1ubuntu1 Courier mail server - ESMTP over SSL ii courier-pop 0.58.0.20080127-1ubuntu1 Courier mail server - POP3 server ii courier-pop-ssl 0.58.0.20080127-1ubuntu1 Courier mail server - POP3 over SSL ii courier-ssl 0.58.0.20080127-1ubuntu1 Courier mail server - SSL/TLS Support ii courier-webadmin 0.58.0.20080127-1ubuntu1 Courier mail server - web-based administrati -- Regards, Robert ----- Robert Penz ------------------------------------------------------------------------------ Enter the BlackBerry Developer Challenge This is your chance to win up to $100,000 in prizes! For a limited time, vendors submitting new applications to BlackBerry App World(TM) will have the opportunity to enter the BlackBerry Developer Challenge. See full prize details at: http://p.sf.net/sfu/Challenge _______________________________________________ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
