Comments on Greylisting - fight Spam with Postgrey and Postfix on Debian and Ubuntu
There are numerous ways to prevent spam from reaching your inbox, the most popular is probably SpamAssassin. Greylisting will not replace spam filtering software like SA but it will serve as a powerful first hurdle for spam thus reducing the ammount of spam entering the system at all.
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Interesting timeing. I just got done installing sqlgrey on my Sarge
box. This has more knobs to tweak than postgrey seems to, and
overall should scale better. The downside is that it's not
packaged for Debian. :-( Just RH and gentoo.)
http://sourceforge.net/projects/sqlgrey/
The setup for postfix-gld is just as easy and you can manage the lists directly through mysql. Tutorial to setup postfix-gld: http://wyae.de/docs/greylisting/
Good tutorial for postfix-gld!
There are a fairly large number of greylisting softwares and they are not very well known so I'm glad to see tips and opinions about them in the comments.
One of the deciding factors for going with Postgrey for me was acually that I did not want any SQL database server. I suppose Sqlgrey with SQLite would have been an option but I like to keep to stuff that is in Debian stable for production use.
//ErkThis howto threw me off and never worked. Turns out newer postgrey is different and/or RedHat configures it differently.
Following the CentOS howto makes everything work again.
http://wiki.centos.org/HowTos/postgrey
Yeah the author should probably say that this guide it's for debian/ubuntu only.
used yast2 to install on opensuse 11, had to edit /etc/sysconfig/postgrey
then commented out
#POSTGREY_CONN_OPTIONS="--unix=/var/spool/postfix/postgrey/socket"
and uncommented
POSTGREY_CONN_OPTIONS="--inet=127.0.0.1:10031"
then changed port from default 10031 to 60000 in this line
after that it worked by restarting postgrey
On my box the default port was not 60000. Run `ps aux|grep postgrey` after you start it and it will show the port on the command line.
smtpd[7976]: warning: connect to 127.0.0.1:10023: Connection refused
it seems postgrey now uses ipv6 as default - so change the line
POSTGREY_OPTS="--inet=127.0.0.1:60000"
to:
POSTGREY_OPTS="--inet=60000"
and everything is fine..
Nice tutorial. Works perfectly and saved my customers from the ransomware locky !
But you have to be warned that postgrey has trouble when sender domain has multiple smtp servers (load balance), the delay can be many hours. To avoid that, you need to whitelist these domains (like gmail or yahoo).