procmail - using {} won't deliver to mbox

Question

I'm trying to use procmail to tidy up some old email into my thunderbird mbox file, however I can't seem to get it to file into an mbox file when using braces. Doing the simple test below with and without braces provides different outcomes - what am I missing, please:

SHELL=/bin/sh
# --- OPTIONAL, USED FOR DEBUGGING (comment out)
VERBOSE=yes
LOGABSTRACT=all
LOGFILE="procmail.log"
MAILDIR=/home/jake/windows/Thunderbird/Mail/Local\ Folders
DEFAULT=/home/jake/done/

# goes into MAILDIR/processed
:0
processed

# goes into DEFAULT/msg.gAmAAAAA4F/etc.
:0
{
processed
}

tripleee · Answer 1 · 2021-03-14T12:31:53.997

Your second recipe is basically a syntax error, though the Procmal parser actually parses it into an expression which however means something totally different than you intended. Here's what you have actually written, spelled out in full.

:0
{
  processed=''
}

So Procmail enters the braces, performs the assignment, exits the braces, and delivers to $DEFAULT when it falls through to the end of the recipe file.

To actually deliver into a file, you need a full recipe like

:0
{
    :0
    processed
}

... but obviously the outer recipe with the braces is completely redundant here.

The fact that a symbol on its own gets parsed as an empty variable assignment which clears the variable named by that symbol is unobvious and wildly confusing not only to beginners, so don't feel particularly bad that you couldn't figure this one out.

With VERBOSE=yes you should actually find that the log file shows you exactly this chain of events. Your log file will end up in your MAILDIR so perhaps you didn't find it...?

procmail - using {} won't deliver to mbox

1 Answers1