a simple way is to create ~phil/.qmail-default containing
|if test "$EXT" '>' `date +%Y%m%d`; then echo address expired; exit 100; fi
followed by delivery instructions for the successful case. You may, of
course, choose to replace the simple one-liner with a script checking
that $EXT really has the form of a date, etc.
I used something like this a long time ago, and then I used these
addresses for my usenet postings, thinking that any spam generated
for these addresses would sooner or later get stopped. It wasn't a
great success, and it ended up pissing off a friend when he tried to
respond to a usenet posting of mine a couple months after I had posted
it. But spam for these addresses, including garbled versions including
only the date, kept coming for years after I stopped doing this.
Оригинал см. по следующему адресу Temporary email addresses Тут же можно посмотреть и другие реализации этой идеи.