Download: http://www.courier-mta.org/download.php

There've been a couple of reports in the past stating that IMAP_USELOCKS was required to keep some clients from misbehaving.

This build reimplements this option with dotlock files, replacing the previous implementation that used a lock file. This implementation should work with NFS and AFS.

Additionally, the new implementation will take advantage of FAM's services (the File Alteration Monitor) if it's available on the build platform. If FAM is present, it will be used to wait for the dotlock to be released, instead of polling.

I'll wait to see the reports from the field, where the IMAP_USELOCKS option is enabled; with or without FAM. If everything works correctly, it should be possible to use FAM to implement real-time updates in the IDLE extension on platforms that use FAM (Irix and all current Linux distributions, according to FAM's web site FreeBSD and Solaris apparently works somewhat also), so that when the same folder is concurrently opened by multiple clients, folder updates from one client are immediately reflected in the other clients.