When I wrote,
| > Bennett Todd has recommended swatch, about which I am thoroughly ignorant,
| > so it may be better than what I'm about to suggest.
Bennett explained,
| I'll expand on swatch just the teeniest little bit ...
| Swatch is a daemon. ... If you can run a daemon, then swatch may well be
| the easiest and best solution ...
| However, there are lots of settings where users cannot run a daemon, no
| matter how efficient. Most ISPs don't let users run daemons (though mine
| does[1]).
Then it's a very rare exception. Many don't even let users use cron and at.
Some allow daemons on the highest, most expensive levels of service or permit
them for a surcharge.
| [I]n a great many settings, solutions like the complex history-tracking
| scripts described by others, or the very simple solution you describe with
| the cookie file, are the only way to get there. Of course your cookie file
| solution will only work if the user is allowed to create a cron job. But
| then there's that procmail recipe intended to work sorta like cron....
Yes, I do the last on another ISP where users are locked out of cron. It is
good for spotting the first message of the day and forking a script, but if a
day goes by with no incoming mail at all, you're out of luck. (And yes, it
uses a cookie file to store the date of the most recently received message.
I also use a cookie file arrangement on the host of my mailing list for a
recipe that adds a plug for the host to the first post of the day and every
fifth post thereafter.)