Unable to Set a Permanent Mail From Address in Postal When Using a Custom Domain

[ofekifergan]

Description
I am using Postal and attempting to send emails from a custom domain (e.g., netflix.com), which I do not own. However, the Mail From address is automatically changed to psrp.netflix.com, and the emails fail to reach recipients.

Expected Behavior
I want to configure a permanent Mail From address to prevent Postal from modifying it, ensuring that the envelope sender remains constant.

Actual Behavior
The Mail From address is dynamically changed to a subdomain (psrp.netflix.com), which does not exist or have valid SPF records.
As a result, the email is rejected due to SPF failures and DMARC policies of the target domain.
This behavior prevents successful email delivery.

Steps to Reproduce
Set up Postal with a custom sender domain (netflix.com).
Attempt to send an email from user@netflix.com.
Observe that the Mail From is automatically changed to psrp.netflix.com.
The email is rejected due to authentication failures.

Question
Is there a way to configure Postal to enforce a static Mail From address instead of it being dynamically modified? If not, can an option be added to control this behavior?

Additional Context
This issue is particularly relevant when attempting to use a domain without ownership. While SPF and DMARC failures are expected in such cases, the dynamic alteration of the Mail From makes it impossible to send emails at all.

[willpower232]

from a custom domain (e.g., netflix.com), which I do not own

If you don't own the domain and its DNS, or can't ask the owner to include the SPF and DKIM records, then even if you modify Postal to let you do what you want to, your messages will probably never be delivered for failing basic spam checks.