Email paragraph 1 to a CSV file

I have my customers fill out a form for their address online and it comes to me formatted as comma delimited (i.e., first, last, address, apt, city, state, zip). This is sent as the first paragraph of the email.

I want to be able save these out to a text file but only of the emails I select (or the ones that are Unread) so I can import the comma delimited text file into my address database in FileMaker Pro.

So far, I have this but it doesn’t work. I end up with just the last email paragraph in the text file. Can anyone give me a little guidance on how to make this work or, at least, tell me what I’m doing wrong?

property list_path : "/Users/User Name/Desktop/test.txt"

tell application "Mail" to try
		tell message viewer 1 to set selected messages to {first message of beginning of (get selected mailboxes) whose read status is false}
		set thisMessage to a reference to item 1 of (get selection)
		tell thisMessage
			set custAdd to paragraph 1 of content
		end tell
	end repeat
on error
	display dialog "You've reached the end of the list"
end try

do shell script ("echo '" & custAdd & "' >> '" & list_path & "'")

return custAdd

Our process is the following: (and what you need to know in parens)

*Save Emails as individual text files (select emails, save emails to folder)
*Read each text file, extract info, write csv into a txt file (read file, extract info using AS text delims, write to file)
*Run predefined FM script to import the csv file (FM run script)

We do individual txt files from our Mail program to a) allow us to serialize each submission and b) store each submission separately from our email program / server.