Resolving CONF-19321 has a few documentation implications.

The general fix is that instead of adminstrators.action returning a list of e-mail addresses for the configured administrators of the site it will now give you a form which you can use to e-mail all the administrators of the site. This is preferable since it doesn't give the user any information about who these administrators are (e.g. the old mechanism of supplying their e-mail addresses could make it easier to guess the usernames of administrators for the site).

This mechanism is linked from the 500 error page in Confluence. It is also linked in 3.3 onwards from the template and theme configuration pages for a space.

Conditions to watch out for:
1) If there is no mail server configured for the site then instead of a contact form you will receive a message telling you that - "No mail server has been configured so it is not possible to contact the site administrators via this method."
2) If none of the administrators for the site have e-mail addresses you also get a message instead of the form - "None of the site administrators have e-mail addresses set so cannot be contacted via this method."
3) If you have removed the confluence-administrators group then you receive the same message as in point 2. (I know this isn't quite correct but you could argue it avoids giving out specific details the user set up of the instance. There wasn't enough time to add handling for this specific condition.)
4) If SPAM prevention/Captcha is configured then those configuration settings will also apply to this form

Configuration Options
1) As mentioned previously, the site wide SPAM prevention settings are used here.
2) There is a new General Configuration setting called "Custom Contact Administrator Message:". This allows you to change the prompt that is presented before the form.
3) There is a new General Configuration setting called "Contact Administrators Form". This allows you to turn the form off. This should be used in conjunction with the previous setting explaining your alternative contact mechanism.

I've attached a few screenshots to help illustrate things.

If you would prefer me to write (or provide a first draft of) the documentation please just get back to me with a location for where it should live and I'll do it immediately.