In a standard event displayer, below the page name/link you have a line with "edited by " followed by the user image and its name/link.

The problem is that, when the wiki is private, the image does not work.

I indicated Gmail because that's my use case, but I assume the same is true for various mail clients and especially for non browser based mail clients (but it probably works on some mail client which are less inclined to cleanup the mails than Gmail).