I asked Ginette from JST how to do this, and here is her response:
Ok, so basically one’s profile image can follow you/your email address where ever you go but for that to happen you need to create one through Gravatar or at least this is what we’ve done in the past. I’ve just tested it and it worked fairly quickly but can take up to 24 hrs according to their website.
Here are the steps we gave folks when we were on the old forum and what I just did with my personal email address
You'll need to upload your profile picture to http://gravatar.com/ and here's how to do that:
First, create an account at http://gravatar.com/.
Once at the Gravatar website, click the “Sign In” button and create an account.
When creating an account, make sure to use the same email address that you use for the forums.
Once you’ve uploaded your photo to Gravatar then it will auto-appear next to your postings.
Let me know if they still have problems and we can see what else can work