Outlook will not spell check signatures

[Eric]

We have a signature with an image at the top, and text at the bottom. We
are wanting to type in the space between the image and the text. when
Word is set as the email editor, spell check will not work in the
signature area. Is there any switch to make Outlook check the signature
by default?

Google has confirmed this is the situation, but there is not solution
(that I have found) to make it automatic. I can do it on an individual
basis.

Thanks