sendmail Performance Tuning

7.6. Summary

• If an email server sometimes runs out of memory, it may not be memory bound. Swapping can be a symptom that the system has run out of “something else,” which has caused processes to back up on the server. This problem eventually leads to memory exhaustion.

• I/O-bound email servers are a common occurrence. Generally, fixing this problem requires adding disks, upgrading storage systems, or upgrading filesystems.

• Often, if a system is network bound, it will be impractical to upgrade the network in the short term. Instead, the email server may need to be upgraded to support deep queues and many concurrent processes.

• When a server becomes saturated, very often the best option is to just let it “work its way out of a jam,” rather than trying ...