Top 5 questions on IT Outage Communication

In your system outage notifications to business users, do you state:

1) WHAT is the problem at hand? WHAT is the business impact? (be careful not to include technical jargons)

2) WHY did the problem happened (root cause)? If not known yet, assure your users that investigation is in progress

3) WHEN is the estimated resolution time? or WHEN is the next update on the problem if you cannot provide a estimatd resolution time yet?

4) WHERE to get more information or status update on this problem? a support website?

5) WHO to contact for questions or feedback?

At the very basic level, this communication is emailed to your users. Hopefully your distribution list includes only relevant people and does not miss out any one who needs to know. My current preferred method is RSS feeds because it is non-disruptive to users and they can subscribe/unsubscribe as they wish.