My error in not being complete with the initial question.

Her concern seeing the originally sent email from her machine with the correct font being returned absent the font was not seeing the signature incorrectly when it came back but wondering if the signature was correct (as sent by her) when opened on the recipient's machine.

Does the fact that the signature returned has a font but the incorrect font mean that the recipient's machine:

1. read the email as rtf, changed the font accordingly and sent it back as such
2. didn't have the font and substituted

?