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Microsoft 365 - Exchange Online

New: Microsoft Defender Quarantine 

OIT will be migrating email safety and security technology to Microsoft 365 on Tuesday, June 6, 2023. This change will mostly run in the background to improve anti-SPAM, anti-malware, and phishing protection for the CU Boulder Campus, but you will start to see notifications that you from Microsoft Defender Quarantine. Visit the Microsoft Defender Quarantine page for additional information and instructions for releasing emails from quarantine.


  • Users can use a desktop email client or use Outlook on the web
  • Email and shared calendaring with up to 100GB of storage space, and message size up to 150MB
  • Improved Outlook on the web (same functionality across all modern browsers) and tight integration with Microsoft 365 suite
  • Global address list including name, department and phone information for all faculty, staff and students 
  • Email contact data for all people, resources, and groups in Exchange Online environment
  • Accommodates multiple personal calendars, group calendars, and resource calendars for scheduling of rooms, equipment, and more

Microsoft 365 Login & Multi-Factor Authentication

Access your Microsoft 365 online applications with a combination of your and IdentiKey password. Please note: only will work for accessing Microsoft 365 applications, not the common preferred email address format of (as shown below).

Microsoft login with identikey-correct

microsoft login w first last - wrong

CU Boulder faculty, students, and staff are required to log in to Microsoft 365 using Multi-factor authentication. Multi-factor authentication (MFA) increases account security by requiring multiple forms of verification to prove your identity when signing into an application. Visit OIT's MFA page for more information, set up instructions, and frequently asked questions about MFA.


Outlook on the Web

Exchange Online offers a web browser-based email and calendaring client through the university's Microsoft 365 subscription called Outlook on the web. If you have previous experience using a browser-based email program like Gmail, Outlook on the Web is the most similar experience. For users new to Outlook, we recommend visiting Microsoft's Getting Started guide for basic instructions.

Visit the Outlook on the web page for the full list of Email and Calendaring tutorials compiled by OIT for campus users.

Best Practices

OIT has put together Best Practices for those that use the delegation feature to manage their calendar in Exchange Online. Visit the Exchange Online Calendaring Best Practices page for more.

Outlook for Windows, Mac or Mobile

OIT recommends that users who would like to set up an Exchange Online account with a mail client use Outlook on their desktop and/or mobile device. Refer to the following tutorials to help set up your email client:

Other Email Clients

You may also use other email clients that support Microsoft's "Modern Authentication" technology. When you log into a client that supports Modern Authentication, you should be directed to a Microsoft 365 login page to enter credentials; you should not be asked to save those in the client itself.

Older clients may not support Modern Authentication and will not be able to connect; for more information on this change, please refer to Microsoft's Improving Security statement.

Microsoft Exchange Email Client Standards

Microsoft Exchange Online is the default email and calendaring solution for all CU Boulder faculty and staff. OIT highly recommends the use of either the Outlook desktop or mobile application or Outlook Web Access for email and calendaring on macOS/iOS. OIT has provided documentation to configure the Apple Mail client for Exchange, but cannot support the application past this initial configuration because the vendor does not consistently adhere to Microsoft's Exchange standards. In addition, OIT does not have the means or access to receive escalated support from the vendor.

Warning: If you have delegates assigned to your inbox or calendar, or you are a delegate of someone else’s inbox or calendar you must use a Microsoft Outlook client or application. Using the Apple Mail app in this manner can result in mailbox and calendaring corruption for both you and the delegate.

Delivery Location

Faculty and Staff are encouraged to use campus email delivery in order to comply with CU's Record Retention Policy. If you are concerned that this will interfere with your academic or research pursuits, you may request an exemption to utilize a different delivery location.