On the user page https://sourceforge.net/users/pander is a gravatar used that is resolved on the private email address from the user.
Since the private email address or at least its gravater is not publicly associated with the sourceforge user account, this gravatar should not be shown at all. This might indirectly reveal personal information that the sourceforge user would not like to communicate to the outside world, especially when the user has no further control over this.
Please use the gravatar for only the user.sourceforge.net email address, not for the private email address. In this way the user has complete control over which kind of avatar is associated publicly with his or her sourceforge account.
Implementing this improves privacy of the user and prevent possible embarrassment or unintended association.
Further comments from the user (before I posted any reply):
Apparently when one creates a gravatar for @users.sourceforge.net email address, this is used by default over the gravatar of the private email address. This should be made clear in the documentation and on the form to manage the user account.
Also I'd recommend not to use the gravatar of the private email address at all and make it clean to the user what is happening so he or she only needs to worry about gravatar of @users.sourceforge.net and knows that NEVER a gravatar of the privare email address will be used.
Hmmm, still the @users.sourceforge.net account is not used as the preverred one. This might be concluded from https://sourceforge.net/u/pander/profile/ (hence my previous post) but is not the case for https://sourceforge.net/users/pander