Hopefully the following may be of some help to others. I had a similar problem as Todd. Here is a part of his thread:
http://www.mail-archive.com/[email protected]/msg59929.html In my case, an existing NT4 Imail installation was moved to a new, very fast (P4-2.4GHz/512MB) Dell PowerEdge running W2K, hardware RAID, Imail 7.13, and KWM 3.0. The result? We had inexplicably slow logins, flaky mail downloads, GLACIAL webmail, and random SMTP/POP hangs--and all with CPU utilization near ZERO. Oh yeah, and a lot of ticked-off users!! Anyway, after a week of debugging, hardware swapping, cloned testbeds, performance logging, and analyzing over 200 MB of packet captures, I now have it humming along quite nicely, thank you. The usual caveat here: The following fixes worked for me, your mileage may vary. :) 1. My dual-homed Dell server was equipped with an Intel Gigabit ethernet integrated into the motherboard, along with an Intel Pro100/S NIC. I noticed in a post that Todd extracted from Ipswitch TechSupp the stunning admission that Imail is incompetent at reliably communicating with two popular server adapters: http://www.mail-archive.com/[email protected]/msg59332.html Guess what? Tech support is right. My tests showed that Imail would randomly just stop communicating for varying periods of time over these two adapters. This particular "going into limbo" issue was resolved by replacing them with two 3C905C's. Note that to fully eliminate this issue, it was necessary to completely DISABLE the onboard Gigabit Ethernet adapter in the server's CMOS setup. The second Intel Pro adapter card was also physically removed from the box. ISSUE SUMMARY: No fast, server-quality NICs are allowed within sight of an Imail box. Ipswitch apparently wants us to continue running the latest 1998-era hardware. :) 2. Packet captures indicated that Imail did not like operating over a NIC with more than one IP address assigned to it. This may be somehow related to the Imail programming blunder of binding to all IP address. Inexplicably, the speed of the machine may also play a role, since an identical multiple IP setup cloned to a P2/266 had no such Alzheimer's issues. And yes, the Imail address WAS the primary IP. The fact is that removing the second IP on this P4 made a HUGE difference in Webmail stability and speed. It doesn't make sense, but as I said, YMMV. ISSUE SUMMARY: Only one IP address per NIC on a Pentium 4 box running Imail. 3. Once the above was sorted out (users--especially WebMail--noticed a HUGE difference in performance and reliability with the two fixes above), there was still a mysterious 1.5 - 6 second delay on some incoming SMTP and POP sessions. The cause? In this case, it was NetBIOS name lookups timing out. To verify the problem, look for this unanswered NBT query request string in your packet captures: "*<00...(15)>" Without getting too involved in the machinations of NetBIOS or of our internal network and firewall layout, basically Windows 2000 (or perhaps a 'getHostAddress()' call by Imail) was insisting on performing an unnecessary reverse lookup (computer name from IP address) on the incoming connection. It was sending a node status request directly to the perceived source--my NAT Public IP address (the equivalent of a "nbtstat -A <ip_address>"). The irony? After NetBIOS repeatedly times out and finally gives up trying to resolve the name, W2K then simply ignores the timeout and successfully proceeds with the SMTP/POP connection! Sheeesh! The solution? If the NetBIOS query can't be resolved with properly configured WINS/DNS, go into the HOSTS file (systemroot\winnt\system32\drivers\etc\) on your Imail box and give the IP address query that is timing out a name to satisfy the lookup. In my case (failing to resolve the NAT Public IP), this is what it looks like: 127.0.0.1 localhost #existing entry ... ... #more existing entries 207.178.203.99 anyname.mydomainname.com #BINGO! Note that the NetBIOS timeout issue was not present on an otherwise identically configured NT4 box. ISSUE SUMMARY: Look for unexplained response delays of multiples of 1.5 seconds. If you have them, sniff the wire (make sure to check ALL interfaces on multi-homed boxes!) for unresolved NetBIOS queries. If necessary, simply create a suitable Hosts file entry to make Windows happy! By the way, the Hosts file is checked every time name resolution is attempted. Changes in it take effect immediately and do NOT require a reboot! As I said, the box absolutely rocks now. I don't claim to know why some of these fixes worked, just that they did. Perhaps this will provide a helpful starting point to others facing similar inexplicable slowdowns. Cheers, Dev -------------- Dev Anand, MCSE,CCNA,A+ Network Manager Biomorphic VLSI, Inc. Westlake Village, CA 91362 dev_at_biomorphic_dot_com pcpro_at_vcnet_dot_com To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
