On Tue, 3 Sep 2019 at 07:52, Benoit Panizzon <[email protected]> wrote:
> 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: > > <Aloï[email protected]> > > We use Postfix 3 but have NOT enabled SMTPUTF8 support. It's also not > advertised in the 'ehlo' reply. > > So I wonder, why is postfix accepting sender email addresses with > invalid characters? I have tested with netcat, indeed 8bit chars are > being accepted. > > We use MIMEDefang as a milter, so I could basically try filter 8bit > sender there, but I would rather use the built in mechanisms of > postfix, if such one exists. > It is no longer against RFC to use international characters in email address, see RFC6530..3. Therefore Postfix 3+ supports SMTPUTF8 by default unless you *disable* it with smtputf8_enable = no. Bear in mind that you may reject legitimate incoming mail.
