[Dovecot] [PATCH] LMTP: Permit user IDs containing recipient_delimiter

The Dovecot 2.1 LMTP server currently always strips the address extension from a recipient address (if recipient_delimiter is set), meaning user IDs cannot contain the recipient delimiter character, e.g. "user+foo" is not supported.

This was surprising for me, as Postfix behaves differently in this regard: It first looks up "user+foo", and only then "user".

The attached patch works for me and brings Dovecot's behavior in line with Postfix. Please let me know what you think about it.