The correct way to invoke procmail for extension addresses is "|/usr/bin/procmail [options]"
Ignore the IFS=".." stuff in the procmail man page.
-<h2>MailBox formats</h2>
-Email can be saved to mailboxes or maildirs by using the correct lines in a
+<h2>Mailbox formats</h2>
+Email can be saved to mailboxes or maildirs by using appropriately formatted lines in a
.forward file:
<p>
-Mailbox format files "/debian/home/foo/Mbox"
-<br>Maildir format files "/debian/home/foo/MDir/"
+Mailbox format files "/home/foo/Mbox"
+<br>Maildir format files "/home/foo/MailDir/"
<p>
To deliver to /var/spool/mail/foo use a construct like '|/usr/bin/procmail