Subject: Re: My own copy of procmail

From: [email-masked] (David W. Tamkin)
Date: Wed, 29 Mar 1995 00:14:25 -0600 (CST)

Richard Coleman wrote,

| Procmail is a benign program.  Without root privileges, about the worst you
| can do would be to trash your own mail drop or home directory.  It's no
| threat to the system or other users.

There is one situation at least where procmail can cause trouble, and that's
hangs as it tries to deliver across partitions or between CPU's.  Be sure to
include directories on as many machines and filesystems as you can when you
have it run the lockingtests or just plain hotwire the makefile to have
procmail use only dotlocking without kernel locks.

---

From: [email-masked] (Gardner Cohen)
Date: Wed, 29 Mar 1995 07:20:38 -0800

Richard Coleman wrote:

   Procmail is a benign program.  Without root privileges, about the
   worst you can do would be to trash your own mail drop or home
   directory.  It's no threat to the system or other users.

Procmail is as benign as Mr. Atom.

I've more than once set off a chain reaction sendmail storm thanks to
a typo in my .procmailrc; each message generated two bounces, and so
on.  After the second time, I resolved to never deploy a change
without isolating it and testing is separately, but even trivially
botched trivial changes can have devastating effects.  It's easy to
imagine this crashing (or effectively disabling) some OSes if
unattended due to eating up process table entries.  Once started,
these problems are difficult to stop as the system degrades terribly
making monitoring and process killing difficult.  If done on a mail
server rather than a single user workstation, these mistakes can cause
others to lose mail, and require someone with root privileges to clean
up the mess.

I think anyone who's read this list for very long is aware of how
easily people misunderstand and misuse procmail.  As a former sysadmin
who had some feeling of the ability of various users to cope with
something as complicated as procmail, I can understand the reluctance
some might have to open up this particular pandora's box.

A secondary issue is the problem of users causing themselves to lose
mail thanks to misapplication of procmail.  The number of times David
Tamkin and others have had to point out missing lockfiles in recipe
fragments posted here should give some idea as to how much mail is
being lost out there.  You can be sure that once one user successfully
uses procmail, there will be other, less capable ones will emulate
them and get into trouble; if understanding procmail isn't in the
sysadmin's job description, it soon will be.