message-yank-empty-prefix

message-yank-empty-prefix is a variable defined in `message.el'.
Its value is

">"

Documentation:
*Prefix inserted on empty lines of yanked messages.
See also `message-yank-prefix' and `message-yank-cited-prefix'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.