Found the problem. Solved

[Robert Chalmers]

sudo ln -s /usr/local/Cellar/mysql/5.6.25/lib/libmysqlclient.18.dylib /usr/local/lib/libmysqlclient.18.dylib

shown by error

Jul  3 09:46:08 zeus dovecot[2223]: imap-login: Disconnected (disconnected before auth was ready, waited 24 secs): user=<>, rip=127.0.0.1, lip=127.0.0.1, TLS: Disconnected, session=<ImCRVxRw5AB/AAAB>
Jul  3 09:46:14 zeus dovecot[2223]: auth: Error: dyld: Library not loaded: /usr/local/lib/libmysqlclient.18.dylib
Jul  3 09:46:14 zeus dovecot[2223]: auth: Error:   Referenced from: /usr/local/libexec/dovecot/auth
Jul  3 09:46:14 zeus dovecot[2223]: auth: Error:   Reason: image not found
Jul  3 09:46:14 zeus dovecot[2223]: auth: Fatal: master: service(auth): child 44250 killed with signal 6 (core dumps disabled)
Jul  3 09:46:14 zeus dovecot[112]: master: Error: service(auth): command startup failed, throttling for 60 secs


Somewhere along the line, the link got removed ? Watch out for updates

Robert Chalmers
https://robert-chalmers.uk
author at robert-chalmers.uk
@R_A_Chalmers