Edited tag value for staging vs prod site

We have two WP sites, one for staging/dev and one for production. We prefer to have the “From” field in the email that is sent from the form to be from the appropriate site. To clarify, if someone is testing the Staging site the email’s “From” field value should be, for example, “[email protected]” but if the form is filled out on the actual Production site, then the “From” field value should be, for example, “[email protected]”. When the Staging site value is hard-typed in the Mail panel’s “From” field, this same value is then promoted to the Production site when we promote the whole site at the same time.If the domain could be a variable/tag it would work on both sites.

I see that there are special mail-tags, so [_site_url] provides me with the URL for the site, but I am not skilled enough to know if I can remove the “https://” in the URL to just get the domain. Is that possible?

I have also been looking at “custom form-tag” ideas but have not found any way to use some regex or editing expression to get the domain from the URL or any other way to get the domain of the site where the form is being submitted from.

Thanks.