Dovecot submission announces CHUNKING but backend Postfix does not support it

[Robert Schetterer]

Am 20.09.2018 um 11:04 schrieb 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

that "may" version depend

http://www.postfix.org/features.html
...
Postfix 3.4 	SMTP server support for RFC 3030 CHUNKING (without 
BINARYMIME).
...

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