Connection dropped by IMAP server

Hello Everyone, I need some help!

We have an Xserve G5 running 10.4.2 Server as our mail server. On-campus, people use Entourage to get their mail; off-campus they use Squirrelmail.

Here's the problem: Now and then a user will not be able to use Entourage to connect to their email account. Squirrelmail also doesn't work and when they try to login in SM, they get the following error: "ERROR: Connection dropped by IMAP server."

I used 'ps -ax' to view all processes on the mail server. There are a bunch (like 30) lines that say 'imapd: localhost [::1]' with no username afterwards. Also, in Server Admin's Mail Service window, there are a bunch of lines (about 30) in the Connections pane that have no username and the address is localhost. My guess is these are Squirrelmail sessions that didn't completely close because the user didn't click Sign Out or something. Just a guess. I don't know. I also don't know if this is related to my problem, or another issue going on at the same time.

Anyway. So, let's say johndoe gets the "dropped by IMAP server" error. There is a line in 'ps -ax' that says 'imapd: localhost [::1] johndoe user.johndoe' and for the life of me, I can't kill the process. I can kill everything else.

So I stopped the Mail Service via Server Admin and refreshed the Connections pane. Everyone disappears except johndoe. 'ps -ax' shows all other connections are gone except johndoe. Start Mail Service, johndoe still gets "dropped by IMAP server" error when trying to login.

So I tried to restart the server via Apple menu, Restart. Server hangs after dock and desktop items disappear. Just shows background...endlessly. Have to hold down Xserve power button for 5 seconds. Wait a few seconds, turn it back on, everything boots up fine. johndoe can now log in.

Seems trivial, eh? Well, I've had this happen to two other users in the last 2 months. If the pattern holds, johndoe's account is likely to do this again a few times in the next week. I'll have no idea why and no way to fix it except restart the entire server. And I think that's awful that I can't resolve this issue without cutting off ALL email access to resolve one account. But anyway. Plus, johndoe will not receive any email while this is happening. Messages to him get put in La La Land. I can't find them to deliver into his mailbox once he can log in again. Grrrr. I'm guessing they're just lost forever.

Does anyone have any ideas? Have you seen that SquirrelMail error before? Does anyone know which log files I should start monitoring to maybe find more answers??? (Please be specific: for example, tell me the full location.)

Thanks for your help!

Posted on Sep 15, 2005 5:06 PM

37 replies

Nov 2, 2005 4:59 AM in response to Patrick Young2

Anyone found a solution? This problem is BIG to us. We have almost 1000 users and have to restart our XServe mail-server several times a day. The hanging processes just ignore a "kill -9" (never seen that before).

If you have a solution please post...

Thanks, Steven

Nov 3, 2005 5:28 PM in response to Steven Muellener

Ok I found out that you can reboot your the server with "reboot -qn" even if there is a process which can't be killed by "kill -9". Thats a beginning.

But somehow IMAP-connections to the XServe can get really dead for instance if a user gives a commend in squirrelmail (rename or move or ...) and than press the cancel button in the browser.

Nobody has made this experience or found a solution for that problem? (Logs show nothing strange to me)

Steven

Jan 13, 2006 2:30 PM in response to Steven Muellener

It's Patrick again. I don't know how or why but I haven't had my original problem in months. I don't know if 10.4.3 fixed the problem or one of the various security patches that came out but for now our mail server is running as great as it can.

🙂

D Little

Level 1

10 points

Jan 26, 2006 12:00 AM in response to Patrick Young2

Hopefully, you all have got this licked. I haven't. This is my first attempt at an OS X Server. I have been a do-it-yourselfer with linux servers for several years though, but not an expert. I appreciate any help from anyone.

The problem is similar. I originally had the mailserver set up with imap 100 max connections. The Outlook clients kept losing their connections. I found this post and read the above and the logs looked very similar. I increased the connections to 10,000, which is very overkill. The problem still occurs, but not as frequently. The current connections are nowhere near 10,000, so the number of available connections doesn't seem to be the only problem.

Any ideas? Thanks in advance.

Feb 8, 2006 5:03 PM in response to D Little

I am seeing very similar issues - I too have just increased my IMAP connections from 100 to 300, will wait and see. We are getting the issue about 1 a week - possibly linked to our Retrospect backup - I have also taken our mailserver completely out of Retrospect.

Final point is: when the Mail process is down, I also can't do much else - I can ARD in, but I can't do ps -aux for instance - it just hangs. I can't launch Terminal (have to leave it open), can't even do ls -l (ls works). Seems as though the 'process maker' is old and busted 🙂

Attempting to shutdown -r just results in me being kicked off ARD, and the mail server just sits there inaccessible until someone uses the power button.

Any thoughts?

D Little

Level 1

10 points

Feb 14, 2006 11:18 PM in response to Michael Cutter1

I decided not to go headless and am glad I did since I've had many problems administering remotely, mostly with WGM, but also with terminal. ServerAdmin is ok, but limited.

My client machines are WinXP using Outlook. Both ethernet adapters on my server are on the same subnet. My problem with dropped/stuck IMAP connections was fixed after I found and fixed a reverse DNS lookup problem on my server, and on the WinXPs added a second WINS server by adding the second ethernet adapter IP on my OS X Server. I don't know which of the two things I did fixed it, or if it was the combination, but after that I haven't had a recurrence of the problem.

Pejvan

Level 1

0 points

Mar 6, 2006 9:02 AM in response to Patrick Young2

i have the same problem here with 10.4.4 server.
all of the sudden, squirrelmail won't allow anyone to login. restarting the mail and web services won't fix it.

I'll try a reboot later, outside office hours...

Mar 6, 2006 3:04 PM in response to Michael Cutter1

Well it hasn't happened in a month since increasing the connections! So all you who are seeing the same problem as I was, please try increasing your IMAP connections and see what happens. If this is a solution then it needs to be documented. Question is whether it's Squirrelmail that's sucking up all the IMAP connections, or something else?

Mar 7, 2006 4:26 AM in response to Michael Cutter

dammit!!! Today it happened! With 300 IMAP processes available, no Retrospect backup, etc - and once again my bloody mail server seemed to run out of the ability to launch new processes, requiring a physical reboot.

Sigh...

Pejvan

Level 1

0 points

Mar 8, 2006 1:31 AM in response to Michael Cutter

I guess we are facing one more Kernel level bug.
Do you have a dual processor or a single one?
I bet this only happens on dual ones 😟

newdude

Level 1

10 points

Mar 17, 2006 1:37 PM in response to Michael Cutter

I have run into the same situation a time or two. I had one user have 30+ connections to the server and caused it to crash. After increasing the number of connections allowed it has seemed to calm for now.

I have found that keeping server admin open will eat up the CPU. I have to actually quit the server admin program and things take a minute or so and goes back down to 15% instead of 99%. Can get a good view of this when the activity viewer is open.

Could be a connection in the two, or simply two different problems.

Mac OS X (10.4.5) Server

Mar 27, 2006 4:36 AM in response to Patrick Young2

I have been having the same exact problem as Patrick. I just installed the 10.4.5 update and set Max connections to 10,000 and hopefully this is behind me. Does anyone have a real answer or solution to this yet?

Mar 27, 2006 11:18 AM in response to Garrettri

I just started having this problem in the last week or so, and I don't know why. Exact same symptoms, the messages in SquirrelMail, everything... and I am only on 10.3.7!

My only hope is to rebuild the mailboxes after making a new /var/imap structure...

Mar 30, 2006 4:49 AM in response to Patrick Young2

The 10.4.5 update and 10,000 connections limit has not helped. Ironically this problem only seems to happen when Mac clients connect to the server. Windows Thunderbird clients never cause the stuck connection. Has anyone found a resolution!!! My mail server has become useless and no one seems to know how to fix it. Thanks for any help.

D Little

Level 1

10 points

Mar 30, 2006 5:21 PM in response to Garrettri

My problem went away. I think what did it was fixing a reverse DNS problem. Reverse DNS pointed to a virtual doman instead of the actual domain. I haven't had the problem since.

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Connection dropped by IMAP server