[Dovecot] Disable multiple POP3 logins

[Marten Lehmann]

Hello,

> With some POP3 servers,  when you login more than once, the POP3 server says 
> "Err: multiple login". How can I achieve that with dovecot ?

this is nothing that's really useful. At your ISP, this is probably due 
to a lockfile if messages are stored in the mbox-format, because if two 
processed would modify your mbox-file, the file would get corrupt. The 
disadvantage is clear: If the process dies for whatever reason, the 
lockfile wouldn't be removed and you could never login again until you 
call the pop3-administrator to manually remove the lockfile. Also, you 
couldn't check for new messages with webmail, while your email-client is 
downloading an email with a very large attachment.
So far about the benefits and drawbacks of blocking multiple logins, 
however, I can't tell you if dovecot is capable of preventing parallel 
logins.

Regards
Marten