How does one properly format a text file?

I'm creating a text file attachment to an email. When the user opens the attachment, the formatting is bogus. It appears that the formatting that would normally produce a new line is showing as a little square box, presumably an unprintable character. (I use the "\n" technique to creating new lines, but it does not seem to be working out as hoped.) Thus what should appear as multiple lines shows as just one very long string of text. How does one create a text file that when opened in notepad or wordpad etc, will be formatted according to one's desires?