A program that sits waiting for calls, and then either directs them to a BBS, performs an echomail (FTN) interaction (sending mail, receiving mail, transferring files, etc.), rejects the call, or chokes and dies and turns your modem speaker on and makes your computer whine. Often run by a series of complex and kludgy batch files. A front-end package was an essential tool for any sysop who wanted to participate in an echomail network, because the vast majority of BBS programs, even if they could accept callers on their own, were unable to send and receive echomail packets. A front-end mailer often had the additional advantage of having more stable modem routines than most BBS software - many sysops used a mailer even if they did not use echomail.