.forward and /dev/null

Just a quick tip for you out there and a reminder for me. If you are using .forward files with your MTA (so, real users, not virtuals) and you want to discard everything received by that user, just put in his/her .forward


"|cat > /dev/null"


Remember that the quotes, they are mandatory (if you’re copy’n’pasting this, change the quotes because WordPress loves to change things)

Maildrop and the automatic maildirmake problem

If you are using a vanilla maildrop in a classic postfix (or another MTA) environment, you will have your master.cf to look like this:

maildrop unix - n n - - pipe
flags=DRhu user=vmail:vmail argv=/usr/bin/maildrop -d ${user}@${nexthop} ${user} ${nexthop} ${sender}


for example. And with this configuration, maildrop will not elaborate at all your /etc/maildroprc directive file. Why? Very simple (once you discover it): because we are using the -d switch which implies the Delivery mode. And it’s even written in the maildrop man page! Look:

Delivery mode

maildrop is the mail server’s mail delivery agent. maildrop runs in delivery mode when no filename is specified on the command line. maildrop
changes the current directory to the user’s home directory, then reads /etc/maildroprc, then $HOME/.mailfilter.

so, what’s happening here? Maildrop check if the ${user}@${nexthop} home directory exists and since it doesn’t, it simply exits spitting in your face :) So, no maildroprc rule applies, so you cannot create on-the-fly the homedir.
Now, there are two solutions:

1. create manually (well, in the user-creation script) the home directory plus the Maildir with something like this:
   mkdir -p /home/vmail/domains/$DOMAIN/$USER
maildirmake /home/vmail/domains/$DOMAIN/$USER/Maildir
chown -R vmail:vmail /home/vmail/domains/$DOMAIN/$USER

2. edit master.cf to be like this (in the maildrop part):
   
maildrop unix - n n - - pipe
flags=DRhu user=vmail:vmail argv=/usr/bin/maildrop /etc/maildroprc ${user} ${nexthop} ${sender}
then give 0600 permissions and vmail ownership to /etc/maildroprc and finally append this to it (if you want to enable maildrop filter capabilities)
USERMAILDIRFILTER="/home/vmail/domains/$DOMAIN/$USER/.mailfilter"
DEFAULT="/home/vmail/domains/$DOMAIN/$USER/Maildir/."
`[ -f $USERMAILDIRFILTER ]`
if ( $RETURNCODE == 0 )
{
include $USERMAILDIRFILTER
}


PS: Gentoo maildrop version is affected by this “problem”. On the other hand, Debian’s one seems to be “immune”