My mailcow server acts as a relay host for my webserver. I created a “mailbox” for which I disabled the sender check and use this account with smtp auth from my webserver => works great.
but: for some sending domains I want my mailcow server to relay that message to another SMTP (AWS SES) instead of trying to send the message itself.
For this I created a Sender-dependent transport and linked some domains to use this transport: when I use the test button this works great.
However when I send a mail from my webserver with a from address of one of these domains, it still tries to deliver this message itself instead of using the desired transport.
What could be the reason for this/how to fix?