.Net System.Mail.Message adding multiple “To” addresses

EDIT: This question is pointless, except as an exercise in red herrings. The issue turned out to be a combination of my idiocy (NO ONE was being emailed as the host was not being specified and was incorrect in web.config) and the users telling me that they sometimes got the emails and sometimes didn’t, when in reality they were NEVER getting the emails.

Correct Syntax for Generating HTML Email using AlternateView

I’m trying to use the AlternateView to cater for both HTML and Text clients. I would prefer to use HTML and only fall back to text where necessary. I started re-coding an old console app to do this but I still have carriage returns and newlines as “/r/n” in my code and my problem is trying to figure out how and where to use Environment.Newline instead of these?