dovecot - Dec 2014 - Is the mdbox format backwards compatible?

I'm contemplating using dsync with dovecot-2.2.10 (el7) and then
transferring
the resulting mdbox files to a dovecot-2.0.9 (el6) server.  Is the mdbox
format backwards compatible between the two versions?

Thanks,

  Orion

-- 
Orion Poplawski
Technical Manager                     303-415-9701 x222
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       orion at nwra.com
Boulder, CO 80301                   http://www.nwra.com