See Microsoft's KB article at
http://snurl.com/ol_autoreply.
Outlook remembers the senders so only one copy of your reply gets sent
regardless of how many times that sender sends you e-mail. This list of
remembered senders is retained only within a session of Outlook; if you
restart Outlook then all the prior senders are forgotten (so don't try
to run Outlook as a scheduled event in Task Scheduler to somehow make it
load, do a mail poll, and then exit). Since spammers auto-generate
bogus e-mail addresses on every "crop" of spam they proliferate, you'll
be replying to each instance of their spam. However, this depends on
where you position the auto-reply rule amongst your other rules. If it
is positioned after any spam-catch rules that have the "stop processing
more rules" clause then they will catch the spam and the subsequent
auto-reply won't get executed.
Note that you must leave your computer powered up, you must leave
Outlook running, you must configure Outlook to schedule the mail polls,
and you probably need to disable standby mode in Power Options (the
network card or dialer may not work in standby mode).
A server-side solution works better. The reply is immediate (or very
soon after receiving the inbound e-mail) and you don't need to waste
power leaving your computer on with Outlook always running. Outlook is
not a reliable "server" for automatic replies (or for anything over a
long period of time). Maybe your ISP already provides an auto-responder
feature which is called vacation response, out of office,
auto-responder, or some other name. You either use their webmail
interface to enable the auto-responder and specify what message to
return or you go to a web page to administer your e-mail account and
configure it there.
