I am having trouble finding the SOAP API for Sales Owner E-mail Address. I tried exporting field data but cannot find it in there along with the other Sales Owner fields such as Sales Owner First Name, Sales Owner Last Name etc.
I think the only one of the Owner * fields available via API is the ID (as sfdcLeadOwnerId).
Curiously, though, you can create another field and copy the value (using Change Data Value) and then access that field via API. Not sure why it needs that workaround. Most likely, there's some hard system-not-even-read-only setting from many years ago that can't be changed.