SpamAssassin won’t do much if it hasn’t been trained. While it does come with a few plugins enabled for DKIM, SPF, RBL, and content checks, SpamAssassin is limited unless you train its Bayesian filter. The Bayesian filter will compare past content from known spam and ham emails to determine the likelihood of spam. Bayes' theorem, named after 18th-century British mathematician Thomas Bayes, is a mathematical formula for determining conditional probability.

Are you curious about SpamAssasin’s sa-update tool and what it does? As with many other programs geared towards servers, there are additional tools that are run inside of cron jobs and used by administrators. Knowing what these tools do and how they work can help you better understand your server and fix issues down the line. The sa-update tool is used to pull new configuration files and rules from channels. These new files are used by SpamAssassin to classify emails as spam in addition to the Naive Bayes filtering.

Keeping your MySQL server backup as current as possible is important. I’ve seen (and have done this myself) people backup using mysqldump once a day, week, or month without any backups in-between. There are a few problems with backing up your database this way. The first problem is that running mysqldump is very slow on large databases and could lockup your website for a significant portion of time. Secondly, you can lose all data that occurred since the previous backup.

Below is a glossary of terms often times used when discussing Virtual Private Servers, web hosting, and networking. Knowing what these following terms mean should help you navigate hosting provider websites and tutorials. Not all of the following terms are concrete in meaning and could be used to mean a slightly different concept. The glossary below is ordered alphabetically and tries to focus only on terms used when discussing virtual private servers.

Having a VPS provider that offers internal IP addresses and internal networking can greatly improve your app or website performance by removing the network latency between servers. In addition to improved performance, an internal IP address you can help improve your servers security by not publicly exposing services to the public. Keep in mind that some internal networks have other VPS clients on the same subnet. These clients can access your internal IP address.