Quoting Michael Ghens (michael(_at_)spconnect(_dot_)com):
Is this a function of sendmail being the local mailler??
Yes. I believe that qmail can be set up to do something similar.
(For those wondering, sendmail can be configured to effectively
ignore the part of the name following the +, so that
user+otherstuff(_at_)your(_dot_)host is the same as
user(_at_)your(_dot_)host(_dot_) This
allows people to filter their incoming mail, for example:
a person might recieve mail at me+business(_at_)site(_dot_)com and
me+pleasure(_at_)site(_dot_)com and set up procmail to treat them differently.
Other than turning on the option, it requires no intervention
from the administrator, unlike aliasing.) I have a faq pointer
around somewhere, which I'll find and post if no one else does.
Mike Stone