Insert External Link

Right now there isn’t a way to use an external image with my plugin, or with get_avatar in general. You can specify an image URL in the $default variable (see: get_avatar), but it still gets processed through gravatar.com.

If you’re maintaining all of the users yourself (meaning you don’t need a fancy interface), you could use a custom user meta field and store the image URL in there, then retrieve it with get_user_meta rather than using get_avatar.