🚀 go-pugleaf

Back in the DIM times MMDF used to use "." as we would use
"%",  that is, as a routing indicator in the local address.
To mail to CSNET sites, for instance, you sent to
    user.host@udel-relay
Since there were a bunch of people that used .'s in their user
names, it eventially got replaced with %.  (Johns Hopkins actually
changed all the periods in their user names to underscores to
avoid the problem).

In any case, the local host these days should NEVER do ANYTHING
with the stuff to the left of the @-sign.  ANy attempt to be
clever here is doomed to fail.  Pretty much % and . should be safe.
I'd make a special warning about "!" in mailbox names as this
does frequently cause problems (even if ! is in the porition of the
address outside the <>).  However addresses with both !'s and @'s
are subject to ambiguity about whether the ! binds tighter than the
@ (depends on which side of the gateway you're on).

-Ron