is there a mail app that does this?

[dep]

quoth Collins Richey:

| Others may chip in. I'm not aware of a mailer that does this
| directly, but there are plenty of scripts for dynamic updating of a
| random tagline in a fixed place that the mailer can scarf up.

do you know the location of such a script and, perhaps, the format of 
the tagline file or files whence it makes its choice?
-- 
dep

The secularists have not wrecked divine things; but the secularists
have wrecked secular things, if that is any comfort to them.
				    -- G.K. Chesterton, "Orthodoxy"