This feels a bit useless because I found posts on this topic about 2 years old. 
Anyway, it would be super helpful to have an HTML editor when creating an e-mail signature. 

The creation of random signatures manually is a true nightmare for the company branding 🙈

Is there any plan for this feature in Pipedrive? 
Other than that, we are really enjoying this tool. Unfortunately thanks to this we cannot use it fully, because any time you want to send an e-mail, we need to send it via our e-mail provider. :-/ Which sucks.