I'm created my signature using HTML. I have a FB, Twitter, etc for my company. When I try to link my sites to the signature, they don't work. Unless I used the actual URL instead of how I want the text to be displayed. It should read like this:

Join The Porter Group on Facebook, Twitter, LinkedIN and YouTube!

When I format this way and send myself a test email, the text is not linked to the URL. I have to use the actual URL as the text in order for it work and that looks messy. Any advice on how to fix this?
Thank you