Email not checking

[zboyblue]

This is driving me CRAZY!!!!

I have Plesk 7.5 Reloaded and inthe past I had Plesk 6 .. in both cases I have had this problem ..

In outlook I have about 12 different accounts.... 99% of the time at least 2 of the accounts fail to check. It is not always the same account and there are no messages in webmail that are not clearing out. The message is always "The connection to the server was interrupted..." Sometimes restarting Outlook or the computer seems to help but not always, may be a coincidence.

PLEASE PLEASE someone help me figure out what is going on, I can't take this anymore!

Craig

 

[jamesyeeoc]

Have you tried increasing the Outlook Account Advanced settings to increase the default timeout value from 1 minute to a higher value?

I have seen newer versions of NAV and McAfee email scanners and spam scanners cause larger than normal delays, resulting in timeouts (yes, even though you tell Norton to protect against timeouts).

In 99.9% of the cases I have dealt with, increasing the value to 2 or 3 minutes gets rid of the problem.

 

[zboyblue]

I think I tried that in the past and it didnt work. Can you tell me what I should check in NAV to see if it is causing the problems? Also, how can the timeout being 2 minutes make a diference? I mean it only takes seconds to check the mail ... so I think maybe I dont understand what the timeout is all about ...

Could you explain? : )

Craig

 

[jamesyeeoc]

I don't fully understand what Outlook is doing with their timeout either, I know it does not take that long to check emails, but for whatever reason, I have seen it make a difference, no rhyme or reason.

With the newer 2005 versions of NAV and NIS, NSW I have seen this problem occur with much more frequency. The other test option would be to set Norton to not scan incoming emails and disable the additional 'Threats' categories. JUST AS A TEST to see if that makes a difference for your clients, it did for each of my clients who has experienced this problem, hence why I ended up setting Outlook's timeout higher.

 

[zboyblue]

I tried all that and still no dice. Any other ideas?

 

[jamesyeeoc]

Have you used webmail to check if there is a SPAM mail with &nbsp or other malformed items which may be gumming up the email retrieval? This is also an old problem.

And if you or the client are using Outlook 2003, then definitely download the latest updates for it. I have seen many other posts on other forums where 2003 users are having lots of connection problems...

 

[zboyblue]

Yea, I checked that and that was not a problem. I checked all the accounts that I use and none of them had any messages like that.

I am using Outlook XP (so the one before 2003)

Any other ideas?

 

[mgalloway]

I ran into this before, but I can't remember how to fix it. There is a variable that controls the maximum number of connects from the same IP, so it will only affect those with more than X email addresses that check e-mail simultaneously from the same IP.

Does anyone know what parameter controls this?

 

[zboyblue]

OOH! That sounds like the problem right there!! If someone knows where to increase the limit that would be awesome!

Craig

 

[jamesyeeoc]

Originally posted by mgalloway
I ran into this before, but I can't remember how to fix it. There is a variable that controls the maximum number of connects from the same IP, so it will only affect those with more than X email addresses that check e-mail simultaneously from the same IP.

Does anyone know what parameter controls this?

Are you referring to the MAXPERIP option for IMAP? (not qmail related)

Or did you patch your qmailsmtpd with the rate limit patch?

Or had you played with your /etc/tcp.smtp file?

Or were you thinking of the /var/qmail/control/concurrencylocal and concurrencyremote files?

Any of this jog your memory??

 

[zboyblue]

I am not sure about any of this, which ones could cause this problem?

I just need to have qmail allow email checking of several email accounts from one IP at one time.

Please let me know if you know what to do to fix this problem.

Thanks so much

Craig

 

[zboyblue]

Ok someone at 4PSA told me this was a setting. Does anyone know which setting and where it is located?

I would super duper appreciate it if someone knows and can tell me!

Thanks!

Craig

 

[mgalloway]

Ok, here you go:

Change the MAXPERIP=4 parameter in the following file:
/usr/lib/courier-imap/etc/pop3 and/or imapd

/You should probably also increase the number of pop3 servers.
MAXDAEMONS=40

Hope this helps...

Good luck!

 

[zboyblue]

WOW THANKS!!! I didnt change that setting because the following one seemed more appropriate:

MAXPERIP=4

I changed it to 10 and everything works great now!!!

WOW, THANKS!!!!!

Craig

 

[zboyblue]

Strange .... the setting that I said earlier did do the trick and worked great. BUT for some reason a few days ago it stopped working. I looked at the file again and it was set back to 4! ??

How would this happen?

-zboyblue

 

[eugenevdm]

I was researching a somewhat similar problem. The specifics of the problem was that every now and again our POP3 server became incredibly slow. At this point we noticed many connections by running this command:

root@cm:~# netstat -an|grep :110 |awk '/tcp/ {print $6}'|sort|uniq -c
33 CLOSE_WAIT
2 CLOSING
134 ESTABLISHED
1 FIN_WAIT1
2 LAST_ACK
1 LISTEN
13 SYN_RECV
19 TIME_WAIT

Notice 134 x Port 110 connections.

At this point when we TELNETed to the local server on port 110 we could see the problem, very slow response before you get the banner. In many cases our clients actually phoned to say they are having timeouts. We knew it wasn't the server because we had just recently upgraded the hardware.

We established Plesk uses Courier IMAP and POP3 daemon so that allowed us to do a more generic search of this problem. We also established when POP3 is slow IMAP is flying. First we were put off by this article which indicates due to strict compliance with RFCs Courier's POP3 daemon suffers from performance problems:
http://www.unwin.org/postfix/slow-pop3d.html

What this means is that pop3dserver must read the entire mailbox, character by character, making sure to count all the newline characters twice.

Luckily we also stumbled upon this article:
http://kb.mediatemple.net/questions/259/(dv)+HOWTO:+Raise+Courier-IMAP+Connections

By default, Plesk and the Courier-IMAP email server drastically limit the number of inbound connections to prevent users from opening up too many concurrent sessions. Unfortunately, this restriction can impact legitimate users who have multiple computers connecting to the Courier-IMAP server from behind a firewall or a single computer that runs an IMAP client that takes advantage of mailbox caching.

Plesk comes configured with a limit of 4 connections per IP address and a limit of 40 connections total. Modern IMAP clients such as Mozilla Thunderbird use mailbox caching to open up multiple connections to increase performance. In the case of Thunderbird, it opens up 5 connections by default which is already 1 connection more than Courier-IMAP's default restriction. Add another few computers behind a firewall and those additional users won't be able to connect at all since a single Thunderbird client is already utilizing all 4 connections.

We believe in our case the exact same is happening for POP3 connections as many of our clients come from a single IP and they have Microsoft Small Business Server with POP3 checking enabled.

We increased the limits as per the article, MAXDAEMONS was 40 and is 80 now, and MAXPERIP was 4 and is 40 now, and the problem seems to have disappeared. Parallels should really up the default limits on Plesk to avoid other people having the same problem.