Odd X-sender behavior

[ggwwbb]

When setting up a plain-vanilla SMTP server (Postfix) as a delivery server in Mailwizz, I'm finding that although I indicate postmaster@domain.com as the FROM address when no other address is supplied for the campaign, I'm seeing an X-Sender header as follows:

X-Sender: bounces@domain.com

(This is the email address I've set up as a bounce server.)

Additionally, a run through mail tester shows:

spfquery --scope mfrom --id bounces@domain.com --ip xx.xxx.xx.xxx --helo-id mta1.domain.com :
* pass
* domain.com: xx.xxx.xx.xxx is authorized to use 'bounces@domain.com' in 'mfrom' identity (mechanism 'ip4:xx.xxx.xx.xxx' matched)
* domain.com: xx.xxx.xx.xxx is authorized to use 'bounces@domain.com' in 'mfrom' identity (mechanism 'ip4:xx.xxx.xx.xxx' matched)
* Received-SPF: pass (mailstreet.io: xx.xxx.xx.xxx is authorized to use 'bounces@domain.com' in 'mfrom' identity (mechanism 'ip4:xx.xxx.xx.xxx' matched)) receiver=ns303428.ip-94-23-206.eu; identity=mailfrom; envelope-from="bounces@domain.com"; helo=mta1.domain.com; client-ip=xx.xxx.xx.xxx

So my question: Is this weird/bad behavior? Not sure why the email for the bounce server is showing up in the header and SPF check.

(If it matters, DKIM isn't set up yet. But I have trouble seeing how that would impact this.)

Many thanks for any help you can provide!

 

[twisted1919]

@ggwwbb - i think you see this because of the "Force FROM" setting in the delivery server, which is set to Never.