For applications that don't support Microsoft's MFA (Multi-factor Authentication), you'll need to generate an "app password" to allow it to work around your newly-imposed security.
Once generated, you can use the password as you would your own when prompted by the application. It's important that you do not keep App Passwords (i.e. by writing down, saving in a sticky note, etc.), as they are, by definition, a "back door" into your account, and new ones can be generated at any time, when/if needed.
To create and use an App password:
- Log into aka.ms/createapppassword.
- Click the create button.
- In the Name text box, enter a name for the password (it can be anything, but we recommend something somewhat indicative, such as "outlook" or "skype on my work computer", as you may need to identify it later), and click next.
- You'll be shown your new password. Highlight the password, right-click and hit Copy (or just copy to your clipboard). Do not dismiss the window.
- Wait about 2-4 minutes. App passwords can take a few minutes to propagate and become usable after creation.
- Open your application (i.e. Outlook or Skype for Business), and when prompted for your password, paste in the App password you had copied to your clipboard in step 4. Be sure to check the box for the "remember this password" option before clicking OK.
- Once you've verified that it's working, you can close the App password window or browser tab.
For those making the move to MFA, but already have Outlook configured without an App password, the following video (no audio!) walks you through the process.
Please keep in mind that at the 1:31 (after closing Outlook), there is a trimmed wait of anywhere from a 1 to 6 minute wait until the newly-created App password actually works.
For more information on MFA, see here.