*BSD News Article 46188


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From: Dean Roth <nicdar5@mgic.com>
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: Re: POP3- ERR Maildrop lock busy! Is another session active?
Date: 29 Jun 1995 12:49:01 GMT
Organization: MGIC
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Message-ID: <3su7ft$c78@homer.alpha.net>
References: <3ssggo$a3m@news.computek.net>
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To: sysadmin@ns1.koyote.com

(Stupid Netscape posting code resulted in a partial post in another message, with no 
way to cancel.)

sysadmin@ns1.koyote.com wrote:

>I am using the Pop3 that came installed with bsd 2.0 ( it didnt require

>When a user is inavertalin disconnect, call waiting, idle timeout, etc while
>in their email client when they try to re-establish their email link they get this message:
>
>POP3 - ERR Maildrop Lock busy!  Is another session actibve?

The commonly used POP 3 server "popper" has problems that can result in
"hung" processes. This is particularly acute with dial up IP service. The result
is a locked mailbox and a bunch of processes doing nothing but consuming RAM, and
angry customers. The cure is a fixed popper program.

Popper waits to read input without a timeout in multiple locations. The cure is to 
add an alarm around the read, and gracefully exit.

Part of the problem is also due to the OS thinking a live socket exists with a
terminal server even though the modem connection terminated. Some terminal
servers appear to not reset sockets when sessions end, which should cause the
read() in popper to fail, causing the program to terminate.

Dean