I got somewhat further.
When setting
submission_backend_capabilities = DSN 8BITMIME
in 20-submission.conf, DSN works.
But:
The comment says
Part of the SMTP capabilities that the submission service can offer to the
client (as listed in the EHLO reply) depend on those capabilities also
being
provided by the relay server. These capabilities currently are:
- 8BITMIME
- BINARYMIME
- DSN
- VRFY (always returns 252 without support)
By default, the submission service first connects to the relay server to
determine the support for such capabilities before sending the initial
EHLO
reply to the client. If the list of capabilities returned by the relay
server
is somehow unreliable or it is undesirable to start the connection to the
relay server before the first mail transaction is started, the backend
capabilities can be configured explicitly using the
submission_backend_capabilities setting. This is a space-separated list of
SMTP capability names. This setting is only relevant for capabilities that
depend on support from the relay server: including (or omitting)
capabilities
that are not listed above has no effect. When this setting is
explicitly set
to the empty string, none of the capabilities is enabled. To achieve the
default behavior, this setting must be left unconfigured.
However, I do not see dovecot connecting to postfix after connecting to dovecot-login and entering "ehlo ...".
There is no connect to localhost:587 until transmission of the message has started (and too late to issue an ehlo response...)
regards
I got somewhat further.
When setting
submission_backend_capabilities = DSN 8BITMIME in 20-submission.conf, DSN works.
But:
The comment says
Part of the SMTP capabilities that the submission service can offer to
the
client (as listed in the EHLO reply) depend on those capabilities also
being
provided by the relay server. These capabilities currently are:
- 8BITMIME
- BINARYMIME
- DSN
- VRFY (always returns 252 without support)
By default, the submission service first connects to the relay server to
determine the support for such capabilities before sending the initial
EHLO
reply to the client. If the list of capabilities returned by the relay
server
is somehow unreliable or it is undesirable to start the connection to
the
relay server before the first mail transaction is started, the backend
capabilities can be configured explicitly using the
submission_backend_capabilities setting. This is a space-separated list
of
SMTP capability names. This setting is only relevant for capabilities
that
depend on support from the relay server: including (or omitting)
capabilities
that are not listed above has no effect. When this setting is explicitly
set
to the empty string, none of the capabilities is enabled. To achieve the
default behavior, this setting must be left unconfigured.
However, I do not see dovecot connecting to postfix after connecting to dovecot-login and entering "ehlo ...".
There is no connect to localhost:587 until transmission of the message has started (and too late to issue an ehlo response...)
regards