Problems switching from Send From email account to a different Send From account

After spending about 20 minutes on a detailed email I changed the Send From account.  That instantly erased my email and replaced it with the signature from that account.  No way to retrieve that 20 minutes of work.  It was rather frustrating.
I would recommend that you compare original signature to text in the email and if anything has changed do not replace the email text with the Signature from the updated Send From account. 
This change would help to avoid a lot of frustration.

I don’t see this problem when I change send-to accounts. The signature changes, but the body of the message is unaltered. Even if I put the body below the signature, it remains intact.

In our emails we use a header logo and we type under the logo.  So maybe it is because the text is within the signature.  I did a couple more tests and the same thing happens.  My text disappears.

Ah, I see what you are doing.  You are correct that you are entering text in the signature and it will be erased by the new signature-- I could duplicate this.  My suggestion is to create a mail template that has the image (not part of the signature) then type between the image and the signature.  Then changing the mail-from will NOT replace the message body.

Thanks.  I created a template and that does work.  Nice to have the various options.