#procmail rule to strip [mailinglist@example.com] from the beginning of the Subject line.
:0
#match the list
* ^List-Post: <mailto:mailinglist@example.com>
{
  #f means filter, h means header, w means use original if filter fails
  :0 fhw 
	#The \/ delimits $MATCH
  * ^Subject: \[mailinglist@example.com\] \/.*
  #-f means don't mangle the headers, -I means replace the subject header
  |formail -f -I "Subject: $MATCH"

  #Deliver filtered mail
  :0
  .List/
}