The following code block defines settings for using avatars, which is by default gravatar.com. Gravatar is a Globally Recognized Avatar. An avatar is an image following you from site to site, and the Gravatar service originated from WordPress, where it was used for blogs. You can set the HTTP and HTTPS URL here:

gravatar: 
plain_url: “http://www.gravatar.com/avatar/%{hash}?s=%{size}&d=identicon”
ssl_url: “https://secure.gravatar.com/avatar/%{hash}?s=%{size}&d=identicon”

Another example would be to set it to point to an Office 365 URL (you must be authenticated to Office 365 to use it):

gravatar: plain_url: “http://outlook.office365.com/owa/service.svc/s/GetPersonaPhoto?email=%{email}&size=HR120x120”
ssl_url: “http://outlook.office365.com/owa/service.svc/s/GetPersonaPhoto?email=%{email}&size=HR120x120”