POP3 locking. Is there a way to reduce this "issue"?

[Vladimir Vassiliev]

Yeah, it's really annoying issue.
I can add to your summary that poptimeout option is not very useful because POP daemon may stall much more than its value. It's because of blocking write() call whose timeout depends on TCP settings of host system. For example, with my system defaults timeout reaches 30 minutes. It's possible to play with /proc/sys/net/ipv4/tcp_retries2 (on Linux) to reduce it.

The best solution I could implement is to search and kill all pop3d daemons (there should be only one) belonging to user when he logs on. I do it with pam_exec module. PAM config and script in attachment. It works for me, but my server load is not very big so some race issues with bigger load are possible.

-- 
Vladimir Vassiliev <vova at edu.yar.ru>
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auth        required       pam_unix.so
auth        optional       pam_exec.so debug log=/var/log/kill_pop3d.log /usr/local/cyrus/bin/kill_pop3d

account     required      pam_permit.so
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