Category Archives: smtp

Email Greylisting

First, for the un-initiated, click here to learn about email greylisting.

When email admins talk about greylisting, one of the benefits they normally point to is load on the actual email server but fail to mention supporting systems. I did notice a decrease in mail processing load there as well as my database server.

Keep in mind this is NOT a busy email server. It’s only hosting a couple TLDs.

I noticed an immediate improvement after restarting mail services (I did not reboot the server).

Building a MySQL Capable Postfix RPM

Build Environment:
CentOS 5 x86_64
Postfix 2.3.3 Sources
gcc version 4.1.2 20080704 (Red Hat 4.1.2-44)

2.6.18-164.el5 #1 SMP Thu Sep 3 03:28:30 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux

# Get the src
1) wget http://mirror.centos.org/centos/5.3/centosplus/SRPMS/postfix-2.3.3-2.1.centos.mysql_pgsql.src.rpm

# Install the src RPM
2) rpm -i postfix-2.3.3-2.1.centos.mysql_pgsql.src.rpm

# Install some dependencies I didn’t have
3.1) yum install pcre-devel
3.2) yum install rpm-build
3.3) yum install mysql-devel.x86_64 openldap-devel.x86_64 db4-devel.x86_64
3.4) yum install gcc.x86_64

# Edit SPECS; remove postgres support
4.1) cd /usr/src/redhat/SPECS
4.2) vi postfix.spec and change “%%define PGSQL 1” to “%define PGSQL 0”
# I didn’t want Postgres support
4.3) “%define MYSQL 1” was already defined for me

Spam Bashing

We finally have our spam filtering back in place at kulish.com. We’ve set it to a semi-aggressive filter where pretty much every incoming email is marked with a spam score.

We’re using the postfix+amavis+clamd+spamassassin setup.

While we’ve been doing without it for a few months (using client side stuff until I found time), I still don’t remember it working this well on the last server install.

Here’s a wopper of an email, just after the installation and testing were completed. The receiving parties and server names have been sanitized to protect the marginally innocent (**PROTECTED**).