Dovecot Pro v2.3.6 was released on 7 May 2019. Two new features in this version are described below; additional features and fixes can be found in the Release Notes.
New obox Index Merge Algorithm
This release introduces a new mailbox index merging algorithm for use with obox installations. This algorithm replaces the old, dsync-based algorithm, which was originally designed for two-way syncing of source/destination mailbox data, with an obox-specific algorithm specifically designed to merge obox data structures. The new algorithm fixes all known problems and inefficiencies with the old merging method. The new algorithm has been tested internally over several months, but the old version remains the default for now.
Details on how to configure the new merging algorithm can be found in the Release Notes.
OAUTH2 Password Grant
This release introduces authentication using the OAUTH2 password grant mechanism. This allows, for example, a user to authenticate via their username/password to the external Dovecot proxy node; the proxy node would then contact an OAUTH2 server using this username/password to obtain a token to allow access to the interior Dovecot nodes. This method can replace master user authentication to allow for more secure connections within a Dovecot platform.
Example configuration information can be found on the OAUTH2 wiki page.
