Email clients all render email differently. When a subscriber forwards an email, some email clients make changes to the code of the forwarded message. This can include stripping out certain HTML elements, wrapping your email in a block-quote, or inserting additional classes to your code—all of which can break your design and make the email less functional for the recipient of the forwarded email.
I replied to this a week ago and do not see my reply. So here it is again. I copied first post and tried to explain better.
I have a user that has all newlines removed from his email when he forwards or replies (using Android), to a single Notes user (User B). All other addressees get email correctly, (other Notes users or outside addressees).
User A gets an email. User A wishes to reply or forward an email including user B in send to using his Android phone.
User B gets email (in Notes client) with all newlines/line feeds removed. He gets, as he describes, a wall of words.
When User A reply/forward from his client to user B, the email appears normal.
Email replied/forwarded by User A to all others from Android (except user B), the email appears normal.