I'm using: Mutt-kz + Isync + msmtp + spamassassin + ProcmailMutt-kz, Isync and msmtp are working. I cannot make procmail start automatically when mail arrives. I'm doing everything as non-root user and running Arch Linux. Procmail is installed.Folders structure:$HOME/Mail/Inbox          /Enviados          /Borradores          /Spam          /P-Spam          /TrashMail arrives with this cronjob script:#!/bin/bashmbsync googlemail && notmuch newHere's my .forward with 644 perms.|IFS=' ' && exec /usr/bin/procmail -f- || exit 75 #damianHere's my .procmailrc with 644 perms.PATH=/bin:/usr/binLOGFILE=$HOME/Mail/procmail.logLOGABSTRACT=ALLVERBOSE=YES   DEFAULT=$HOME/MailMAILDIR=$HOME/MailSHELL=/usr/bin/zsh:0fw: spamassassin.lock* < 512000| /usr/bin/vendor_perl/spamc :0fw| /usr/bin/vendor_perl/spamc :0:* ^X-Spam-Level: \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*Spam:0:* ^X-Spam-Status: YesP-SpamIf I run procmail -v I get (only the important stuff):procmail v3.22 2001/09/10Locking strategies:     dotlocking, fcntl(), lockf(), flock()Default rcfile:         $HOME/.procmailrcYour system mailbox:    /var/spool/mail/damianI I run:procmail DEFAULT=/dev/null VERBOSE=yes /dev/null </dev/nullI get:procmail: [1970] Tue Apr 21 22:16:37 2015procmail: Rcfile: /dev/nullprocmail: Assigning MAILDIR=/home/damianprocmail: Assigning LASTFOLDER=/dev/nullprocmail: Opening /dev/nullFolder: /dev/null             
Procmail not running
mutt;procmail
There does not seem to be any easy way to integrate Procmail into isync / mbsync.  I would go for server-side filtering, or possibly abandoning the (as such neat) idea of syncing IMAP with local folders.With that, my original answer probably doesn't matter much, but I have preserved it below.Your .forward file contains a syntax error.  The damian should be a comment # damian but in this day and age, unless you are running a legacy Sendmail from last century, you can just leave it out.Using zsh as your shell for Procmail processing looks weird; try changing that to /bin/sh.  Even if you like zsh, you should probably prefer to avoid its features in Procmail.  Using nonstandard shells has caused hard-to-explain trouble in the past (although the bugs I have seen were with tcsh).You have two spamc recipes.  One should suffice.  The second one should go (spamc itself will refuse messages which are too large, anyway), but I would also remove locking from the first one.Your DEFAULT should probably be $HOME/Mail/Inbox, right?  You don't want mail in $HOME/Mail directly, do you?Other than that, your .procmailrc is unremarkable.For more help, maybe see http://iki.fi/era/mail/procmail-debug.html