Dear AGreer,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Per the description shared, I understand the concern facing at your end ie., when merging the Word document as a Plain Text, the fields with the email address is showing the mail to address as well.
If my understanding is correct, I have test the behavior at my end where I can't reproduce the behavior when merging the document as a Plain Text. So, I would like to request you to share the screenshots of the fields in the data source connected to the Word document and screenshot of the inserted fields in the document.
In addition, if you send an email as HTML, do you also have the same problem?
We look forward to your response. Thanks for your cooperation.
Sincerely,
Mia | Microsoft Community Moderator