can't retrieve large numbers of email

[Ric Otte <ric@otte.ucsc.edu>]

If I allow a large number of emails to build up at my email provider, I have
problems downloading them.  When I run fetchmail, I can download 100-200
of them, but then I get a message such as the following:

reading message ric@otte.ucsc.edu:195 of 399 (10332 octets)  flushed
reading message ric@otte.ucsc.edu:196 of 399 (5552 octets) fetchmail: SMTP connect to localhost failed
fetchmail: SMTP transaction error while fetching from otte.ucsc.edu
fetchmail: Query status=10 (SMTP)

If I then run fetchmail again, I get the following:

ric@perelandra:~$ fetchmail otte.ucsc.edu
207 messages for ric at otte.ucsc.edu (1083211 octets).
reading message ric@otte.ucsc.edu:1 of 207 (5552 octets) ..fetchmail: SMTP connect to localhost failed
fetchmail: SMTP transaction error while fetching from otte.ucsc.edu
fetchmail: Query status=10 (SMTP)

If I wait several minutes (10-15) then I will be able to retrieve
another 100-200 emails, at which point I get the same error message.

I cannot figure out why this is happening.  In my /etc/exim/exim.conf, I have
the following line:
   smtp_accept_queue_per_connection = 2000
which I thought would allow large numbers of email to be delivered.  I
checked /var/log/exim/mainlog, and nothing is written when mail fails.  I am
sending fetchmail through procmail (which also has no error message in the
log file)

If anyone knows why this is happening, or has any suggestions, I would
appreciate it very much.
Thanks,
Ric
ps--in case it is helpful, here are some more parts of /etc/exim/exim.conf
that may be relevant.

local_delivery:
  driver = appendfile
  group = mail
  mode = 0660
  mode_fail_narrower = false
  envelope_to_add = true
  return_path_add = true
  #file = /var/spool/mail/${local_part}

  directory=${home}/Maildir
  maildir_format = true
  prefix = ""


procmail_pipe:
  driver = pipe
  command = "/usr/bin/procmail"
  return_path_add
  delivery_date_add
  envelope_to_add
# check_string = "From "
# escape_string = ">From "
  suffix = ""