NFS File Locking Bug and Mail Delivery

A small number of users with “functional but incorrect” custom procmail rules may have experienced issues with their inbound mail delivery starting yesterday afternoon after the firewalls on the mail servers that handle message delivery were updated to be more secure.  While the new firewall configuration was technically correct, it exposed a previously unnoticed bug with the version of software running on one of our NetApp filer clusters and prevented one of the mail servers from obtaining file locks correctly.  An explanation of the incorrect procmail syntax is in this forum post.  -Kelsey

4 comments for “NFS File Locking Bug and Mail Delivery

  1. Just a note – for users like me, who actually *prefer* their local mailboxes (in their home dirs or subdirs thereof, not their mail dirs) to be in mbox format (easier to search for things and keep things organized in a single file), your warning might make people do the wrong things.

    I have a lot of custom procmail rules like that, but they don’t put things into Maildir, but mbox format. I have about 20 custom procmail rules for dividing up my mail like this, and read it locally with Pine.

    Everything else that doesn’t get put into one of these local mbox mailboxes is left in the default INBOX to be read, also with pine, via IMAP.

    If I’m reading one of my mbox mailboxes, and procmail writes to one of them, I definitely want them locked before being modified.

    Am I the only one who uses procmail in this fashion?

    – Tim

  2. TIm, I doubt you are the only one doing it but I’d encourage you and anyone else to do it differently. Even though you are a shell user I’d suggest that you let the mail servers deliver your mail without filtering with procmail and then run a cronjob that would download your mail and filter it with your procmail rules to your home directory. Either that or switch over to using IMAP.

  3. Kelsey – does doing procmail processing of ANY kind (whether locks are used or not) during emil delivery time, slow down the email delivery process sufficiently that it’s a big drain on resources? Just curious about why you suggest this.

    – Tim

  4. Probably best to take this over to to the forums Tim but to answer the question, procmail doesn’t present any appreciable load to the mail servers upon delivery. I suggested it because I’d rather see you interface to the mail cluster like a regular IMAP or POP client than to be the odd duck out delivering to mboxes in your home dir.

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