Sorry for the noise.
Allowing dovecot server on the postfix relayhost
(https://www.postfix.org/postconf.5.html#smtpd_authorized_xclient_hosts)
permit to retrieve sasl_username in the log :
Nov 10 10:53:13 relayhost postfix/smtpd[2749948]: 834AE3F8AD:
client=dovecot-submission[0.0.0.0],
sasl
Hello,
We would like to use Dovecot Submission to have less queues to maintain.
The relayhost (Postfix) after Dovecot routes mail by sender_map, so
authenticated user, not the "mail from" because .
For what we've seen, we can't use receive header to retrieve this
authenticated_user.
Example
