Delaying Email Delivery Using Procmail and Cron

Because I use Mutt, any mailbox that has new mail tends to get my attention when I check my email. This became particularly annoying because I kept opening my spam mailbox to check a single spam message. Therefore, I decided to come up with a way to delay the delivery of my spam to once per day.

I started by changing my “.procmailrc” to deliver spam messages to a different mailbox that Mutt does not check.

MAIL=`echo $HOME/Mail`
[...]
:H
* ^X-Spam-Status: Yes
$MAIL/delay_spam
[...]

Then I created a new procmailrc file called “spam.procmailrc” that would deliver mail to my checked spam mailbox.

MAIL=`echo $HOME/Mail`

:0
$MAIL/spam

Next, I wrote a short Bash script to use Formail and Procmail to deliver all of the messages in the delayed delivery spam mailbox to the normal spam mailbox.

#! /bin/bash

FORMAIL=/usr/bin/formail
PROCMAIL=/usr/bin/procmail
PROCMAILRC=$HOME/.procmail/spam.procmailrc

MAIL=$HOME/Mail
DELAY=$MAIL/delay_spam
TEMP=$MAIL/.spam
LOCK=$TEMP.lock

# Make sure there is delayed mail and we can get the lock (retry once)
if ( test -s $DELAY && lockfile -r 1 $LOCK 2>/dev/null ); then

    # Add the delayed mail to the temp mailbox and empty the delayed mailbox
    cat $DELAY >> $TEMP && cat /dev/null > $DELAY
    # Process each delayed message
    $FORMAIL -s $PROCMAIL $PROCMAILRC < $TEMP && rm -f $TEMP

    # Delete the lock now that we are done
    rm -f $LOCK
fi

Finally, I set the script to run daily using Cron. Now I am only interrupted by spam when I choose to be instead of every time a new message arrives. I have used the same technique to delay the delivery of emails to unimportant mailing lists so I only read them hourly instead of every time a message arrives.

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