E-mail overload

Lots of info when you google on this subject. We are going to do a staff survey on this built into something called a well-being survey (NOT a stress survey!). Here are some suggested questions:

Question One: Do you receive more than 25 emails a day on average.
(This is more specific than - I often feel overwhelmed by volume of emails I receive). I choose 25 because there is a paper which suggest that this is a tolerance point.

Question Two: The quality of received email (on a scale of 1 to 5)
For example:
Emails I receive are easy to read
Emails I receive are to the point
Emails I receive tell me what is expected of me
Emails I receive tell me when action is required

Question three: The arrival and processing of email (on a scale of 1 to 5)
For example:
Email often distracts me from more important work
Email is too often used in place of other forms of communication
The Subject line contains sufficient detail for me to access the importance of the email

Question Four: Irrelevant email and inappropriate use of the cc function (on a scale of 1 to 5)
For example:
I receive unnecessary email
I received irrelevant / untargeted email

It's a little more than three questions but may get a debate going, and there are some comparators we could benchmark against.