Thanks Brian, I've been monitoring it over the last day or so. There are some hosts that have a fair number of connections at once this is because many of the clients share mailboxes for sales, purchase, marketing etc a number of client machines have as many as 10 mailboxes set up. However Thunderbird is limited to 1 cached connection per mailbox which should give approx. 10 connections per machine I would think.
Checking the logs I have not found anything to indicate the MAXDAEMONS setting was hit (I'd been putting that up for the last week thinking that could be a problem). I've tried increasing the MAXPERIP to 300 but still getting some users having problems on occasion. All this said this morning I have tried to recreate the problem on a Windoz laptop running Thunderbird 2.0.4 as per the other machines on the network and failed to get the problem. One difference between my setup and the other machines is location, the laptop was in my office plugged directly into the network switch the server is on, the other client machines are on the other side of the building ( about 50m ) connected via a switch in that side of the building which connects the the server switch through a CAT 6 cable. Looking at the switch at this end I appear to have inherited a 100m/b link between the servers and the main office ( doh! ). I've just ordered a new Gigabit switch so once I have a sensible infrastructure we'll see what happens. Just proves you can't skip the basics, especially when you start somewhere new. I had assumed the problem was the server because that was something I had introduced, the old server used to sometimes give the same problem but not very often. I figured that the new machine being about 10 times faster and with 4 times the RAM and a gigabit NIC instead of 100mb maybe it was just showing the problem faster ( maybe flawed logic there! ). Watch this space. Thanks again, On Wednesday 27 June 2007 08:47, Brian Candler wrote: > On Tue, Jun 26, 2007 at 11:00:37AM +0100, Adrian wrote: > > I'm having an intermittant problem with all the Windows machines on my > > LAN connecting to Courier IMAP. Error messages is: > > > > Could not connect to server <foo.bar.server> connection was refused > > > > All machines are using Thundbird 2.04 as their IMAP client, machines > > connecting from outside the LAN and my own machine which runs Linux do > > not have the problem. > > > > Total number of similtaneous connections to the server I consider fairly > > low, typically between 30 - 60. > > > > Machine is a Pentium D 3Ghz with 1GB RAM > > CPU rarely hits double figures and generally stays below 5% > > Mem usage is pretty low typically 600 -700 MB free with no swap space > > usage Network Card is a Broadcom 10/100/1000 although looking at the > > output from dmesg there is a line: > > tg3: eth0: Link is up at 100 Mbps, full duplex > > > > which may be relevant. > > > > Any thoughts or suggestions greatfully received. > > Did you see anything in your mail logs? If you have exceeded the MAXDAEMONS > limit (default 40 connections) then you should get a message logged. > > However if you have exceeded MAXPERIP then I don't think you get a log. You > probably should, but the way couriertcpd is written it's not easy to do. > > Use netstat -nt to determine how many simultaneous IMAP connections are > originating from each client. Courier's default MAXPERIP limit is 4, but > some IMAP clients originate 5 or more. If this is the problem you can > either increase MAXPERIP, or you can configure the clients to use fewer > connections. > > Googling for "thunderbird concurrent IMAP connections" turns up things like > http://www.zimbra.com/forums/administrators/1527-setting-concurrent-imap-co >nnection-limit.html which should show you how to adjust the clients. > > Brian. -- Regards, Adrian ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Courier-imap mailing list [email protected] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-imap
