* lmtp/lda: dovecot.index.cache file is no longer fully mapped to
memory, allowing mail deliveries to work even if the file is huge.
* auth: userdb passwd lookups are now done by auth worker processes
instead of auth master process (as it was documented, but
accidentally didn’t work that way).
+ lmtp: lmtp_rcpt_check_quota=yes setting checks quota on RCPT TO.
– lmtp: After successful proxying RCPT TO, the next one to a
nonexistent user gave tempfail error instead of "user not found".
– lmtp proxy: Fixed hanging if remote server was down.
– imap: Fixed crash when SEARCH contained multiple KEYWORD parameters.
– doveadm: Various fixes to handling doveadm-server connections.
– -i <instance name> parameter for Dovecot tools didn’t work correctly.
– director was somewhat broken in v2.1.10. This version also includes
various reliability enhancements.
– auth: passdb imap was broken in v2.1.10.