E-mail attachments constitute a surprisingly large and even
unwieldy subject.  The first clarification is to distinguish
emission of e-mail with attachments, from its reception and
interpretation.  The Wiki page on the [mime] package focuses
mostly on the latter.

The variety of ways to transmit e-mail attachments with Tcl is
large.  [CL] keeps a few models in
[http://starbase.neosoft.com/~claird/comp.unix.programmer/attachments.html#Tcl].