The seemingly endless number of possible mail server configurations is no surprise for most IT support personnel. Whether an organization is operating on a shoestring budget or is well-funded, mail servers are often crammed with unnecessary applications that take up too many precious resources. This dubious practice can cause the mail server to perform poorly even if it’s running on a new, high-performance box.
Take for example a machine that has Microsoft Exchange, SQL, and Active Directory installed along with a different mail server program. The additional mail server program is a trial version that was installed when the administrator noticed that the mail was not flowing as fast as it should have been. When the flow of mail eventually came to a full stop, the administrator contacted IT support.
The administrator had forgotten a crucial fact: Port 25 can only be used by one mail server at a time. Had the administrator bothered to check up on the status of the CPU resources prior to installing the trial mail server program, the call to support may have been avoided. Uninstalling the trial software unblocked the mail flow, but SQL still consumed most of the mail server resources, hence slowing down the flow of mail. The solution: moving SQL to a dedicated server.
In the example above it can be argued that basic common sense may have been forgotten by the administrator while setting up the mail server. Still, the problem is far too prevalent to simply dismiss. The best advice that can be given to administrators in this case is to avoid cramming all major applications in one mail server. In the case of enterprise servers, non-standard configurations must be avoided at all costs.
After numerous calls to support regarding mail server problems, a few rules regarding the administration of a mail server have been compiled:
– A single NIC card should not be configured with 1000 or more IPs. This would quickly lead to degradation of mail flow.
– Microsoft Web Edition Servers should be installed on their own and should not coexist with other mail servers on the same machine. They are simply not meant to be used as classic mail servers.
– Mail server machines should never be over-clocked. This is especially true of enterprise servers. The risk of the machine overheating and all the mail being lost is too high.
– Scheduled audits of mail servers should be performed from time to time. Whenever resources are running low, administrators should immediately look for unnecessary tools and applications that may have collected over time. If an anti spam appliance is installed in the network, it should checked during these audits.
– Redundancy is the best policy. In case of a catastrophic failure, redundancy will redirect the mail flow to a mail server that is not affected.