Fix continuation line causes empty email being sent

[Pietro]

Hi all,
I have recently met a strange, at least strange for me as a Gnus newbie, message
popping up in the minibuffer when sending an email, message says:

"Fix continuation lines? [y/n]"

Such message is shown for each body's line of text and answering yes for all of
them causes the email to be sent with without the body text I entered, in fact
an empty email is sent.

What does "Fix continuation lines" do and why does it get shown ?