1. Go to Settings > Passwords & Accounts, then tap Add Account.
  2. Tap your email provider, for IndigoSlate email please use Exchange
  3. Enter your email address and password.
  4. Tap Next and wait for Mail to verify your account. 
  5. Choose information from your email account, like Contacts or Calendars, that you want to see on your device. 
  6. Tap Save.