It seems that already a bunch of similar posts or issues in this forum exists, but none of them matches my case 100%. So here is another one:

I get this error when Odoo tries to send a mail:

Mail Delivery Failed
Mail delivery failed via SMTP server 'None'.
SMTPDataError: 550
5.7.1 Sender mismatch

The outgoing mail server seems to work ok and I used the same SMTP server in other older Odoo installations with no problems. The thing that puzzles me is the new field FROM Filtering.

I tried several versions of domains or nothing, but it has no effect. I guess this field replaces the mail.catchall.domain entry in the System Parameters. I think that Odoo V17 does not somehow find a corresponding outgoing mail server. And I would like to know which list of comma-separated domain or mail names the FROM Filtering parameter is refering too?