Office 365 + Duo Authentication

Which Office 365 applications require Duo?

  • Microsoft Office 2016, Office 365, and Office 2019 on PCs and Macs
  • Outlook Mobile app for iOS and Android <-- RECOMMENDED
    • If you have an older Android phone, you may need to use the Outlook Mobile app or upgrade your phone as the 'native' mail app does not support 'modern authentication', a requirement to use Duo with the Office 365 service. You can download the app from the app store.
  • Apple Mail (macOS 10.14 Mojave or newer - see Note below)*
  • iOS Mail app
    • Some iOS users may need to remove and re-add their Office 365 accounts to get Duo to work. Instructions on how to do this can be found here. Alternatively, we recommend that you download the Outlook Mobile app from the App Store.
    • Apple provides software support for iOS devices manufactured within the past 7 years. As of 2021, if your device is older than the iPhone 6s and running at least iOS 11, you must use Outlook Mobile. See above.
  • UCI Outlook Web Access (OWA) at

*NOTE: Apple Mail will NOT work with Duo if you're running an older version of macOS, such as High Sierra (10.3). Please use Outlook on the Web ( or you can download your free copy of Microsoft Office and use Outlook for the Mac. Details on how to get the software can be found here. Students can get their free copy of Office here.

Apple officially supports/provides security patches for the current OS version (macOS 11 Big Sur) plus the previous two, so our recommendation is that you upgrade to at least macOS 10.14 (Mojave). Your system could be vulnerable to attacks that are fixed in newer releases, and your system could be compromised and used to attack other systems. In addition, there are bug fixes and security updates to the Apple Mail client that necessitate it being updated to fix problems other users are having and to prevent security issues with older clients.

If you're running an older version than the ones mentioned above, please update your operating system. Faculty and staff should partner their with their local CSC, and students should reach out to AntTech for assistance.

We understand that upgrading your OS can be time-consuming, so in the meantime we recommend using OWA or Outlook for the Mac, as previously mentioned.

The OITHD cannot assist with OS upgrades, and we cannot implement any changes to the network to get your email to work on an older machine. We apologize for the inconvenience.

Do I have to use Duo every time I check my email?

No. The vast majority of our users check their email using the Outlook desktop client or Apple Mail which doesn't require you to enter your password when you open them; therefore, you don't need to use Duo everyday.

You will have to use Duo each day if you check your email via Outlook on the Web (aka OWA) at

Similarly, you'll only have to use Duo with Office 365 if:

  • You get a new computer or device and need to add your account.
  • You change your password. Each device will require you to re-enter your new password, so you'll have to use Duo as your '2nd factor'.

Return to the OIT Help Center.