Dovecot submission announces CHUNKING but backend Postfix does not support it

[Michael Goth]

Hello,

I'm setting up Dovecot 2.3.2.1 as a submission proxy to a Postfix 
backend server. Dovecot announces CHUNKING, but the Postfix backend does 
not support (or announce) it.

HELO from Postfix:

   220 backend.mydomain.com ESMTP Postfix (Ubuntu)
   ehlo test
   250-backend.mydomain.com
   250-PIPELINING
   250-SIZE 104857600
   250-VRFY
   250-ETRN
   250-STARTTLS
   250-ENHANCEDSTATUSCODES
   250-8BITMIME
   250 DSN


HELO from Dovecot proxy:

   220 proxy.mydomain.com Dovecot ready.
   ehlo test
   250-proxy.mydomain.com
   250-8BITMIME
   250-AUTH PLAIN LOGIN
   250-BURL imap
   250-CHUNKING
   250-ENHANCEDSTATUSCODES
   250-SIZE
   250-STARTTLS
   250 PIPELINING


When a client sends BDAT, Postfix closes the connection. Here's a log 
snippet from Postfix:

   < MAIL FROM:<user at mydomain.com>
   > 250 2.1.0 Ok
   < RCPT TO:<some at recipient.com>
   > 250 2.1.5 Ok
   < BDAT 114098 LAST
   > 502 5.5.2 Error: command not recognized
   < Content-Type: multipart/alternative; 
boundary=Apple-Mail-55D35F74-2EB7-4B3B-A607-E421DD71C07A
   > 221 2.7.0 Error: I can break rules, too. Goodbye.


Apple Mail seems to ignore the fact that Postfix does not understand 
BDAT and Postfix does not like that :-)


 From a quick glance at the code it seems CHUNKING is always added to 
the capabilities and that's not configurable. Is this a bug or am I 
doing something wrong?


Thanks,

  Michael