[Dovecot] recipient_delimiter

[Phil Howard]

I have recipient_delimiter = + in main.cf (Postfix).  But deliveries
to dovecot/deliver are still being rejected.  It appears that the full
email is still in the envelope (e.g. phil+how...@example.com which I
want to be delivered to p...@example.com).  Is that how it's supposed
to work and Dovecot just doesn't support this?