Per  BSERV-3112 - Getting issue details... STATUS , it is now possible to configure Gravatar URLs in Bitbucket Server, this can be set in the bitbucket.properties file. The following properties are responsible for this:

• avatar.url.format.http
• avatar.url.format.https

The following format parameters are available for the above mentioned properties:

• %1$s -> The user's e-mail address, MD5 hashed, or "00000000000000000000000000000000" if the user has no e-mail.

• %2$d -> The requested avatar size.
• %3$s -> The fallback URL, URL-encoded, which may be defined using "avatar.url.default".
• %4$s -> The user's e-mail address, not hashed, or an empty string if the user has no e-mail.

So the above parameters can be specified in bitbucket.properties following these examples:

avatar.url.format.http=http://www.gravatar.com/avatar/%1$s.jpg?s=%2$d&d=%3$s
avatar.url.format.https=https://secure.gravatar.com/avatar/%1$s.jpg?s=%2$d&d=%3$s

Disable Gravatar Support:

1. Click the  icon in the Bitbucket header.
2. Click Avatars.
3. Unselect "Enable Gravatar support"
4. Save

If you need to audit this value outside of the UI, you can use this SQL to confirm Gravatr is disabled.  This should return "disabled":

SELECT * 
FROM   app_property 
WHERE  prop_key = 'avatar.source';