[imp] qmail setup

[Lars Hecking]

> If you don't want to receive duplicate messages, try using this
> procmail recipe (modify to your liking):
> 
>     # Kills duplicate messages
>     :0 Wh: msgid.lock
>     | formail -D 8192 $MAILDIR/logs/msgid.cache
 
 Bad advice. This recipe is d_a_n_g_e_r_o_u_s_.

 If you read the part of the procmailex man page below this, you'll see:

>>
     Beware if you have delivery problems in recipes  below  this
     one and procmail tries to requeue the mail, then on the next
     queue run, this mail will be considered a duplicate and will
     be  thrown  away.  For those not quite so confident in their
     own scripting capabilities, you can use the following recipe
     instead.  It puts duplicates in a separate folder instead of
     throwing them away.  It is up to you to  periodically  empty
     the folder of course.

          :0 Whc: msgid.lock
          | formail -D 8192 msgid.cache

          :0 a:
          duplicates
>>