My "sent" emails are being received without the message I typed & sent

I just discovered several of my sent emails from the past week have been received with only my signature, not the message I typed. These emails are going to a variety of email address types (comcast, gmail, professional businesses). I tested a "forwarding" message to another email address I have and it went through fine. I sent another email this morning as a reply and cc'd myself on it  and it was blank. Why would this just start happening?

Thanks!