Last month, Google released rich text signatures for their Gmail product.
When I read this I was excited that I may be able to get rid of the plug-in I had been using for this same purpose. While the plugin worked, most of the time, there were times when it did not. I also personally prefer to use built-in features whenever possible.
I checked out the new Rich Text Signature setting. Quickly I found that it allowed you to add images and links, yet still lacked the ability to do HTML editing. Not yet ready to give up I Googled to see if anyone else had found a way to do HTML in the new Rich Text Signature setting. Finding none I set to figuring out my own solution.
As I thought I remembered that this same feature could be found in Google Sites (and perhaps elsewhere). So I logged into one of my Google Sites and sure enough, the editor was almost identical, except that in the Google Sites editor there is an “HTML” button, which is lacking on the Gmail editor.
I had the idea that perhaps I could use the Google Sites editor to get an HTML signature into Gmail. It worked. Here is how I did it.
I created a new page on my Google Site. I clicked on the “HTML” button to “Edit HTML Source”. I pasted in the HTML I had been using with the plugin. I clicked “Update”. Now my signature showed up in the new Google Site page as rich text. I then highlighted the rich text version, copied it, went to my Gmail settings and pasted it into the Rich Text Signature editor. I saved and the click on Compose. Lo, and behold, there it was. Like magic.
I hope this helps you out until Gmail adds that HTML button to the Gmail editor.