zmailer, zsh makes numbers disappear.

[Felix Lee <flee@guardian.cs.psu.edu>]

If you send mail to "123456", zmailer bounces it back correctly, but
the error says "no such user -" instead of "no such user 123456".

The number disappears because crossbar calls (uucproute "123456"), and
uucproute does a (return "$address"), where address=123456.

The problem is 'return' behaves entirely differently when it's given a
number.  This is a strange problem with zsh.  It looks like this will
also cause other subtle router problems that rarely occur in normal
operation, but will get exposed by the right combination of errors.

Workaround: replace all occurrences of (return $string) with
(echo $string; return), which a little less efficient, but does the
correct thing.
--