🚀 go-pugleaf

Smail (or, at least, pre-3.0 versions thereof) is a UUCP router that
makes a UUCP site RFC822 conformant. It also makes them look like Sendmail
sites (they even ripped off the Sendmail format for Message-Ids). It is
usually quite sufficient for a UUCP machine.

Sendmail is an inter-network mail handler. It is particularly handy on
the Internet since it has built-in the SMTP routines used on the Internet
to move mail around. (Silence, please, from the MMDF disciples in the
back row.) On a more pragmatic level it has some very nifty aliasing
features (like piping mail to a program or saving it in an arbitrarily
named file) that are glaringly absent from Smail. Many sites will never
need those features, but then, some will.

[In this article "Smail" refers to any version that predates 3.0. Version
3.0, which was written from scratch by a couple of masochists at Amdahl,
resembles Sendmail more than it does earlier Smail. It's also not yet
publically available.]