-- begin script
set f to choose file
tell application "Mailsmith 1.5"
	tell message window 1
		make new enclosure at end with properties {file:f}
	end tell
end tell
-- end script

We may be able to provide a general purpose utility in the future (after we better understand the needs and make sure it jives well with the other options in the translator).

Meanwhile, you can use a script I posted awhile back that is a crude way for masking email addresses. Type your address, select it, run the script, and it generates a mailto link.

tell application "BBEdit 6.5"
	tell text window 1
		set s to selection as string
		set entity_s to ""
		repeat with c in s
			set n to ASCII number c
			set entity_s to entity_s & "&#" & n & ";" as string
		end repeat
		set mailto_s to "<a href=\"mailto:" & entity_s & "\">" & entity_s & "</a>" as string
		set selection to mailto_s
	end tell
end tell

and from "bughouse"

give this a try for encoding email addresses: http://www.apple.com/downloads/macosx/system_disk_utilities/spamstopper.html