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Slow IMAP process in Webmail

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9:49 am
December 3, 2009

mariogomide

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Hello Consultant,

I´m having a hard time with my dovecot IMAP server. I´ve got about 8k users. And my dovecot is configured to authenticate against a Win2k3 AD (kerberos, samba and ldap). Also my dovecot is secure with SSL.

POP3s works fine and fast IMAPs works fine and fast with clients other than my webmail – squirreloutlook. No problems with outlook or thunderbird.

Whenever a user logs in or changes to a folder, there is a 2 to 3 second delay to show my folder content, as it shows in my maillog:

Dec 3 12:35:22 server dovecot: imap-login: Login: user=<mario.gomide>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, TLS
Dec 3 12:35:25 server dovecot: IMAP(mario.gomide): Disconnected: Logged out

This doesn´t happen when I open a message, send e-mails or go through the options page.
This is seriously killing my users and myself. I have a test environment that it is 99% the same configuration and software and I don´t have this problem.

Here´s my dovecot.conf:

protocols = imap imaps pop3s
   protocol imap {
     listen = *:143
     ssl_listen = *:993
   }
   protocol pop3 {
     ssl_listen = *:995
   }
ssl_disable = no
ssl_cert_file = /etc/pki/dovecot/certs/certmail.cer
ssl_key_file = /etc/pki/dovecot/private/certmail.key
verbose_ssl = yes
mail_location = maildir:/home/vmail/%u/Maildir
protocol imap {
}

protocol pop3 {
}
protocol lda {
postmaster_address = somemail@domain.com
}
auth_username_format = %Lu
auth_verbose = yes
auth_debug = yes
auth default {
mechanisms = plain login
passdb ldap {
args = /etc/dovecot-ldap.conf
}
userdb static {
args = uid=501 gid=501 home=/home/vmail/%u
}
user = root
}
dict {
}
plugin {
}

What could be this 1% different? My server is surelly not the problem. Plenty of memory and CPU. It is actually "underloaded"

Please help me out.

Thanks a lot!

Mario Gomide

7:17 pm
December 3, 2009

consultant

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Hi Mario,

Please try Kerberos authentication it may fix this issue. You are probably not encountering this problem in the test environment since it is not as loaded as the production server.

7:23 am
December 8, 2009

mariogomide

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I have cloned my production machine into VMWare and, even with no load at all, I still get the same problem.

When I use kerberos, nothing changes…

Could it be related to Apache, php, IMAPs (tls/ssl with certificate) or squirreloutlook?

In my test environment (same platform), I have no problems.

Thanks!

Mario Gomide

7:42 am
December 8, 2009

consultant

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posts 341

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There are a lot of suspects here. How about using the regular SquirrelMail. The problem could be due to Squirreloutlook but I'm just guessing here.

8:10 am
December 9, 2009

mariogomide

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That's my next test. But my test environment uses squirreloutlook and no problems at all.

Anyway, it wont hurt to try.

I also tried this:

Dovecot serves IMAP on port 143 and IMAPs on port 993 and squirreloutlook is configured with the following (conf.pl):

4. IMAP Server            : 127.0.0.1
5. IMAP Port              : 143
6. Authentication type    : login
7. Secure IMAP (TLS)      : false
8. Server software        : other
9. Delimiter              : detect

still no dice…

1:42 pm
December 28, 2009

mariogomide

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Hello Mr. Consultant,

Well, I changed my whole structure to a new server and now my webmail (squirreloutlook) works as fast as it should.

No more problems with slowliness or hanging. Now dovecot was configured from scratch to use pam (kerberos authentication) instead of ldap. I have done this change before on my old server, but with no changes in performance.

And I'm still using RHEL5.4 64bits.

Thanks

Mario

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