In order to comply with Microsoft's modern authentication, some users will need to remove and re-add their email account from within their native iOS Mail app. The following steps can be used to re-add your account.
1) Go to Settings > Mail > Accounts and chose your Villanova account (It could also be named 'Exchange').
2) Select 'Delete Account.'
3) Then click 'Add Account' under Accounts.
4) Select 'Microsoft Exchange' on the account type.
5) Add your email address and a description. Select Next.
6) When prompted on how to set up your account, select 'Sign In'
7) You will then be redirected to a sign in page. Please enter your username@villanova.edu and click 'Next'
8) Enter your password and click 'Sign In'
9) You will then be redirected to your mail app. Once your account has been validated, you should see the following screen.
10) Click 'Save' and your account will be added.