Benoit Panizzon:
> Dear List
>
> We use Postfix / Dovecot on our email plattform.
>
> Lately I have started seeing more and more emails being accepted by
> postfix, but then rejected by the local delivery agent dovecot with:
>
> 500 5.5.2 Invalid command
> syntax (in reply to MAIL FROM command)
>
> Looking at the headers, I see that the envelope sender contains 8 bit
> characters, AFAIK against valid RFC. Example:
>
> <[email protected]>
>
> We use Postfix 3 but have NOT enabled SMTPUTF8 support. It's also not
> advertised in the 'ehlo' reply.
With SMTPUTF8 turned off, Postfix does not enforce 7bit envelope
addresses or headers. All you can enforce is strict_8bitmime=yes
and strict_8bitmime_body=yes. As documented, this can reject
legitimate mail from programs that don't understand MIME.
With SMTPUTF8 turned on, you can enforce strict_smtputf8=yes which
accepts UTF8 envelope addresses only if the client requests an
SMTPUTF8 mail transaction.
> So I wonder, why is postfix accepting sender email addresses with
> invalid characters? I have tested with netcat, indeed 8bit chars are
> being accepted.
Because it is Postfix's job to deliver mail, not to force everyone
else into RFC compliance.
Wietse
