[imp] Prerequisites for horde and imp head

[Max Kalika]

Quoting Scott Martin <martin@math.ohiou.edu>:

> So is it the same thing as sendmail? fetchmail? I don't understand the
> difference. Is it just a preference thing like whether to use MySQL or
> PostgreSQL for your database?

- Sendmail is a MTA (transport agent). It just sends mail from machine to
  machine.

- Procmail is a MDA (delivery agent).  It gets mail from sendmail and
  PROCcesses it.

- Fetchmail could be considered an MUA (user agent).  It gets delivered mail
  from a mail store on remote machines.

All three are separate animals.

--mk23