Ongoing Mail Service Management
Getting a mail server up and running and securing it is only the beginning. As with any other server, a mail server requires ongoing management and monitoring. Whether it is as simple as creating new user accounts and tweaking your spam filters on a regular basis, the job doesn’t end once you’ve confirmed that you can send and receive email. Also, like most other system administration tasks, a proactive approach helps you prevent problems rather than deal with them once they’ve developed.
There are a few things to monitor for Mac OS X Server’s mail services. First, you’ll want to keep monitoring the performance of the server as a whole. You can do this by using the graphs panes in Server Admin. Look at network performance and CPU performance to determine the overall load on the server.
More importantly, look at the storage needs. If you are using IMAP, you can quickly find that your users are storing large amounts of messages that take up a large amount of space. You can monitor storage: overall on the server for the mail service as a whole in the mail service maintenance pane’s Database tab, and for individual users on the Accounts tab. Although quotas help keep users in line with storage limits, understanding which users are regularly approaching their quota (and if there is a legitimate reason) can help you plan for their needs. Monitoring storage can also be helpful for determining whether or not you need to create additional mail stores and which mailboxes should be placed on specific stores.
As with any server, you should keep track of the logs, particularly error logs and logs specifying failed login attempts. You should also keep track of the logs for your firewall (the firewall built into Mac OS X Server, an external firewall, or both). They can help you detect both problems with the server and security threats. Remember that because your users will have a single username and password combination for email access as well as log in to their network account, a compromised password can compromise more than just a single user’s mailbox.
You should also keep track of how well your spam filters are operating. You can do this by using the SpamAssassin logs, anecdotal evidence from your users, or by using a mailbox for all messages marked as spam. Chances are that you’ll find the need to adjust these filters periodically, so being aware of how well they’re operating at any given time can help determine how and when to adjust them.