Resource mailbox reclassification project


Microsoft has a new licensing model that all CU Denver | Anschutz users and systems are transitioning to on January 1, 2020. This new license model requires us to convert all resource mailboxes from licensed user accounts (which they are today) to shared mailboxes in Office 365.

What is a resource mailbox?

A resource mailbox is a legacy mailbox type in Office 365 that is usually for anything but a person. These mailboxes can represent conference rooms, shared equipment, or a department branded email address on a website (example:

What is a shared mailbox?

Shared mailboxes in Office 365 allow a group of users to view and send e-mail from a common mailbox using their own university credentials. They are similar to a resource mailbox in most respects, but they:

  • Do not have a password and cannot be logged into with a password
    • To access the mailbox the user will need to be granted access and will login to the mailbox with their own username and password.
  • Do not require a paid license

How will this impact me and/or my department or division?

  • Passwords for resource/shared mailboxes can no longer be used to access the mailbox.
    • Shared mailboxes will require that access is given by a mailbox owner/administrator.
    • Users will authenticate to shared mailboxes with their own university credentials (username and password).
  • The mailbox size will decrease to 50GB from 100GB

Resource mailboxes used in applications.

Some application administrators have used the username/password included with a resource mailbox to run an application with (runas). Any applications running as resource mailboxes accounts will need to be changed and may stop functioning once converted.

How to get ready for the switch.

If you and your department are already accessing the resource mailboxes as shared mailboxes, you won't need to do anything. When the license switches from a resource mailbox to a shared mailbox, nothing will change.

If you are logging into a resource mailbox using a password, you will need to change how you are accessing them. You can do this now, you don't have to wait for 1/1/2020 to change how you access the mailbox.

Frequently Asked Questions:

Does this change impact my personal mailbox ( or
Answer: NO

I currently have access to one of the listed mailboxes. Will I retain my access or permissions after the change?
Answer: Yes. No changes to access or permissions are being made.

I received the notification that my resource mailbox is being converted. Will it continue to work after the conversion? 
Answer: Yes 

I received a notification but do not see my mailbox in the spreadsheet and don’t know what to do.
Answer: Please contact the OIT Service Desk (303-724-4357) or

My department has a mailbox called and we all know the username and password for that account. This is the way we login. Will this still work? 
Answer: No. The usernames and passwords for resource mailboxes will no longer work after this change. You will need to request full access to the mailbox(es) if you are accessing the mailbox as shown above.

My department has a system or application that uses a resource mailbox. Will my system continue to work?
Answer: It is likely that your application or system will be impacted. Please contact OIT as soon as possible.

My department is accessing a resource mailbox on the spreadsheet through our normal Outlook accounts (using our own university credentials), do we need to do anything?
Answer: No, if you are accessing a resource mailbox using your own university credentials, nothing will change. You will not have to re-add it as a shared mailbox or change the way you log in to see it.

Additional Resources

For a downloadable pdf about adding shared mailboxes in Outlook for PC, Mac and Webmail, use the guides below:

Windows users - How to add a shared mailbox in Outlook

Mac users - How to add a shared mailbox in Outlook