given a string, if it is an EmailAddress, return it, otherwise throw an error.
Use this to parse string input to EmailAddress type to pass to fromEmail (when needed).
This is not meant to be a general RFC5322 (et al) email address validator, which would be more expensive.
given a string, if it is an EmailAddress, return it, otherwise throw an error. Use this to parse string input to
EmailAddresstype to pass tofromEmail(when needed). This is not meant to be a general RFC5322 (et al) email address validator, which would be more expensive.