You didn't post your exact message, found in the Postman Email Log. Assuming your error is:
Invalid e-mail address: /a>Then I think your issue is the same as another known problem in Zerif Lite.
You can fix it by ticking the box "Prevent plugins from modifying this field" in Postman > Configure Manually > Message > Message From Address > Email Address.
Or you can also fix it in the Zerif code itself.