In addition, the appearance of “bare” “CR” or “LF” characters in text (i.e., either without the other) has a long history of causing problems in mail implementations and applications that use the mail system as a tool.
– J. Klensin, Simple Mail Transfer Protocol; RFC 2821; April 2001.
The formatting of email text sometimes gets messed up when it has been forwarded more than once. However, with a little work this problem can be minimized, and can also be fixed after the fact if required. The following sections provide more information: