[HowTo] Replace courier with dovecot

[aseques]

From deliver manual:
-s: Subscribe to mailboxes that are automatically created (via -m parameter or fileinto Sieve action). (v1.1.3+)


It might be that you're using an older versions than 1.1.3 or that this option is not availabel on centOS. Delete the -s part from master.cf and should go fine.