[Assp-test] issue with SRS and vacation message

[Renaud <ma...@no...>]

Hi Guys,

I'm using ASSP to forward local domains on the external email services
of my users.

The normal mail flow is:

(1) external mail --> (2) ASSP (local domain) --> (3) internal postfix
--> (4) ASSP --> (5) external domain

In a normal operation (4) ASSP rewrite then sender address (1) using SRS
method with a domain (Y) bounce.xxx.yy which is declared in my SPF
authorization DNS entries.

The trouble happen when my user in (5) sets a vacation message. In this
case, the new scenario is this one:

(1) external mail --> (2) ASSP (local domain) --> (3) internal postfix
--> (4) ASSP --> (5) external domain --> (6) ASSP [ERROR]

when the (5) external domain receiving an email, it sends an
auto-generated  message back to the sender with the vacation message. To
reply (5) is using the SRS rewrited sender (SRS), instead of the "FROM"
address of (1).

When the email arrive to (6) ASSP I've these messages in the logs:

"[RelayAttempt] <IP ADDRESS> <email address> [SMTP Error] 554 5.7.6 SRS
only supported in DSN"
"[isbounce] <IP ADDRESS> bounce message detected"

After what, the vacation message is never transmited to the original
sender (1) and a bounce message is send to (5) with a delivery issue.


So if my interpretation is right, I've a trouble on the SRS method when
the message bounce or when the final recipient sets an auto-generate
message.

Is someone used this kind of use case before, or have an idea why (5)
use the SRS address instead of the true sender address (1) ?

Thanks for your help
Renaud