V8/usr/src/cmd/Mail/manual/cmds/alternates

.ip \fBalternates\fP
If you have accounts on several machines, you may find it convenient
to use the /usr/lib/aliases on all the machines except one to direct
your mail to a single account.
The
.b alternates
command is used to inform
.i Mail
that each of these other addresses is really
.i you .
.i Alternates
takes a list of user names and remembers that they are all actually you.
When you
.b reply
to messages that were sent to one of these alternate names,
.i Mail
will not bother to send a copy of the message to this other address (which
would simply be directed back to you by the alias mechanism).
If
.i alternates
is given no argument, it lists the current set of alternate names.
.b Alternates
is usually used in the .mailrc file.