Severe problems establishing IMAP connections

[Aidan Evans]

  We are experiencing severe but inconsistent problems with establishing
IMAP connections.  If I do a "telnet imap.server 143" it just sits at

	Trying...
	Connected to imap.UCIS.dal.ca.
	Escape character is '^]'.

Eventually I may get a response from imapd, but other times I never get
through.  Curiously, POP connections have similar problems, but much less
severe; often they get the pop3d banner just about right away, but not
always.

  If I run netstat and look for the incoming connection it sits in
SYN_RECV state for minutes.  When the problem is less severe it gets to
ESTABLISHED, but lsof indicates there is no associated process.

  Could this be a memory shortage?  The machine has two gigabytes.  Right
now "top" shows

Mem:  2059004K av, 2053712K used,    5292K free,   12K shrd,  207400K buff
Swap: 2096376K av,   10088K used, 2086288K free              1383220K cached

and there are about 430 imapd processes running plus 370 sendmails.  The
number of sendmail make it look as though it's also difficult to get lmtpd
started (via a Unix socket).


Name       : Cyrus IMAPD
version    : v2.1.4 2002/04/30 18:06:05
vendor     : Project Cyrus
support-url: http://asg.web.cmu.edu/cyrus
os         : Linux
os-version : 2.4.9-34smp
environment: Cyrus SASL 2.1.2
             Sleepycat Software: Berkeley DB 4.0.14: (November 18, 2001)
             OpenSSL 0.9.6b [engine] 9 Jul 2001
             CMU Sieve 2.1
             TCP Wrappers
             lock = fcntl
             auth = unix
             idle = poll
             mboxlist.db = skiplist
             subs.db = flat
             seen.db = flat
             duplicate.db = db3-nosync
             tls.db = db3-nosync

Aidan Evans   | Networks & Systems
(902)494-3332 | University Computing & Information Services
              | Dalhousie University, Halifax, N.S., Canada