email signature

email signature

When I copy & paste my email signature into the Signature section of the Messages tab within Settings, it looks normal. 
After checking the Enable Signature box, then creating a new message, the formatting is completely off. 
There are spaces between letters within the same word, some letters italicized & others not within the same word, and in some messages there are many spaces between the lines of text in my signature.

I don't see an area where I can reformat this. 

Can anyone point me in the right direction of how to fix this?