just include in /etc/dovecot/dovecot.conf the line with the number of processes ... with this change it should work .. even if your config says it has only 100
And when dovecot reniciar do not get any warning that you want to get too many connections for your configuration in other module
auth_mechanisms = plain login cram-md5 digest-md5
disable_plaintext_auth = no
default_process_limit = 300
and restar dovecot
----
If I include more processes than there are in other modules by default configured when restarting dovecot .. it warns that it is not possible to manage them
default_process_limit = 1000
/etc/init.d/dovecot restart
doveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (3000)
doveconf: Warning: service anvil { client_limit=1000 } is lower than required under max. load (3003)
[....] Restarting IMAP/POP3 mail server: dovecotdoveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (3000)
doveconf: Warning: service anvil { client_limit=1000 } is lower than required under max. load (3003)
Warning: service auth { client_limit=1000 } is lower than required under max. load (3000)
Warning: service anvil { client_limit=1000 } is lower than required under max. load (3003)
you must already configure /etc/dovecot/conf.d other files to readjust the number of processes and connections to your imap