I am only getting the word "TEST" in the body of my email when emailing EFT Remittances to Vendors.

If you are using Mekorma MICR to email EFT Remittances to the Vendor, in the GP Email Message Setup (GP > Tools > Setup > Company > Email Message Setup), you must name the email message "REMITTANCE". Any other name will result in the email body only containing the word "TEST" in it.