setting service_count results in Permission denied

[Micah Anderson]

The load on our machines has gotten too high, so I started to see log
messages that directed me to look at this page for config changes:

https://pad.riseup.net/redirect#http%3A//wiki2.dovecot.org/SocketUnavailable

One of the things I wanted to do on that page was to set the:

service imap { service_count = 100 }

but when I added that to the service imap block, and restarted dovecot,
I see this in the logs: Error:
net_connect_unix(/run/dovecot/imap-postlogin) failed: Permission denied

I dont understand how this impacts permissions. Its clearly this
setting, because when I remove it, things work again. I found nothing
else in the logs indicating a configuration problem.

This is what the config block looked like:

service imap {
  # Most of the memory goes to mmap()ing files. You may need to increase this
  # limit if you have huge mailboxes.
  #vsz_limit = 256M
  # Max. number of IMAP processes (connections)
  process_limit = 4096
  service_count = 100
  executable = imap imap-postlogin
}

service imap-postlogin {
  # the script process runs as the user specified here (v2.0.14+):
  #user = $default_internal_user

  executable = script-login /usr/local/sbin/postlogin_imap

  # this UNIX socket listener must use the same name as given to imap executable
  unix_listener imap-postlogin {
  }
}

This is with dovecot 2.2.13, thanks for any help you can provide!

micah