sendmail Performance Tuning

1.3. Definitions

Before going any further, let’s define some terms used when discussing email services. The Mail Transfer Agent (MTA) is responsible for moving email between different email servers using the Simple Mail Transfer Protocol (SMTP), defined by RFC 2821 [KLE01]. Examples of UNIX MTAs include sendmail, postfix [POS], Exim [EXI], and qmail [QMA]. MTAs temporarily store email that they have accepted but not yet delivered in the message queue (or mail queue, or just queue). The Local Delivery Agent (LDA) is the program that receives email from an MTA and places it in the message store or mail spool. The message store is a data repository where email messages reside, typically sorted by user. A user queries this repository using a Mail ...