What exactly did you delete? Did you delete your email account from the mail server?
What everyone is saying:
Remove your mail account from your phone. Then add it back on.
DO NOT delete your email account!!!
Here's what you should do:
If you use Apple Mail:
Apple Mail supports Modern Authentication by default when you setup the account as Outlook.com. If you use Apple Mail and you are seeing password prompts or connection errors, this is most likely happening because your account got configured as basic authentication. To mitigate the issue, remove the account and add it back as Outlook.com:
- Go to Settings > Mail > Accounts.
- Tap the email account you want to remove from your iPhone, then tap Delete Account. For more information, please go to Add and remove email accounts on iPhone.
Add your account back to Apple Mail:
- Go to Settings > Mail.
- Tap Accounts, then tap Add Account.
- In the Add Account dialog, choose Outlook.com.
