exponential mail queue growth postfix - Connection timed out

[mimo <mimo@restoel.net>]

I am not sure if this is directly related to DEBIAN isp but anyway, 
since people on this list seem quite experienced I might as well ask you.

This is a postfix-1.1.11 running on RedHat 9.0 (not my fault:) - I 
usually have a mail queue of about 500 messages. Last week (and after a 
colleague upgraded and left for Australia) the queue started growing 
exponentially. Today it's about a 2000 messages sitting there (my q-size 
is calculated from 'active' and 'deferred').
I have tried pflogsumm-1.0.4.pl and noticed alot of 'Connection timed 
out' messages:
/var/log/maillog:14153
/var/log/maillog.1:31009
/var/log/maillog.2:31069
/var/log/maillog.3:30377
/var/log/maillog.4:20078
/var/log/maillog.5:18484
/var/log/maillog.6:13999
/var/log/maillog.7:15149
I have found something about concurrent connections which might correct 
this - any ideas?
That's all I know so far. Any help highly appreciated.

Michael Moritz

/etc/postfix/master.cf
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (50)
# ==========================================================================
smtp    inet    n       -       y       -       -       smtpd
#smtps    inet  n       -       n       -       -       smtpd
#  -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes
#submission     inet    n       -       n       -       -       smtpd
#  -o smtpd_enforce_tls=yes -o smtpd_sasl_auth_enable=yes
#628      inet  n       -       n       -       -       qmqpd
pickup  fifo    n       -       y       60      1       pickup
cleanup unix    n       -       y       -       0       cleanup
#qmgr     fifo  n       -       n       300     1       qmgr
qmgr    fifo    n       -       y       300     1       nqmgr
#tlsmgr   fifo  -       -       n       300     1       tlsmgr
rewrite unix    -       -       y       -       -       trivial-rewrite
bounce  unix    -       -       y       -       0       bounce
defer   unix    -       -       y       -       0       bounce
flush   unix    n       -       y       1000?   0       flush
smtp    unix    -       -       y       -       -       smtp
showq   unix    n       -       y       -       -       showq
error   unix    -       -       y       -       -       error
local     unix  -       n       n       -       -       local
virtual unix    -       n       y       -       -       virtual
lmtp    unix    -       -       y       -       -       lmtp
#
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
# The Cyrus deliver program has changed incompatibly.
#
cyrus     unix  -       n       n       -       -       pipe
  flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
uucp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - 
$nexthop!rmail.postfix ($recipient)
ifmail    unix  -       n       n       -       -       pipe
  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp     unix  -       n       n       -       -       pipe
  flags=Fq. user=foo argv=/usr/local/sbin/bsmtp -f $sender $nexthop 
$recipient