I have had the experience that a message prepared in Emailer and read by Netscape mail reads as a long uninterrupted line, until a carriage return is encountered.
This is a bug in Netscape 2.0 that I believe they fixed in 3.0. It was due to an error in managing messages that are quoted-printable. Your messages are probably quoted-printable because you use accented characters.
Any character that requires two or more keystrokes to use is a higher order character (an 8 bit character) that must be broken into a two character (or more) sequence to be sent over the internet, and the message is flagged as quote-printable so the receiving program can properly decode the information.