Catherine Hampton asked,
| I've finally been checking my log file in my efforts to learn
| procmail better the last few days, and have noticed a bunch
| of these messages. They've been happening for a couple of months
| at least, and I haven't been [losing] mail, but I wonder what it
| means.
|
| stty: : Function not implemented
The usual cause for that is that the user's shell is one that reads a startup
file at every invocation, and the startup file contains an stty command,
which makes fine sense for an interactive session at a terminal but none for
delivering mail in the background. Then some recipe in .procmailrc contains
an action line with a character from $SHELLMETAS, so procmail invokes a
shell, which reads in the startup file, and then it can't run stty.
Virtually always the culprits are csh (or a derivative) and the recipient's
.cshrc.
One possible solution is to move the stty command out of .cshrc into .login;
another is to edit .cshrc so that csh runs stty only if the shell is invoked
interactively; a better one, though, is to put
SHELL=/bin/sh # or some other non-csh shell
at the top of .procmailrc to make procmail immune to csh's assorted quirks.