I have a user who developed a WebApp that sends SMTP messages. Users are able to reply to the message using a MUA (outlook, whatever) but there is no NDR if the user doesn't exist.
I suspect that the envelope is empty or missing and only the body is populated with a From.
Since I doubt their ability to fix the problem correctly, I want to offer them suggestions on how to fix this.
Is it correct for me to suggest any of the following (mutually exclusive of each other)
- To Set the FROM address in the envelope, and not just the body
- Ask them to set the header Return-Path:asdf@company.com
- ???