History of sendmail

• sendmail is one of the oldest and most commonly used MTAs on the Internet
• originally written before the Internet was standardized, when each site used their own local mail system and most sites exchanged mail using UUCP (Unix-to-Unix Copy)
• designed to be flexible enough that it could be configured to pass mail between any two different mail systems, regardless of their characteristics

• modern Internet is much more standardized
• the majority of the Internet uses SMTP (Simple Mail Transfer Protocol)
• much of sendmail's historical functions are no longer needed
• even using SMTP, an MTA is still needed to route mail!