Thanks for that info and choosing the Apple Support Communities. If I understand correctly, you are unable to add an additional email account to your iPhone. If you haven't already, please force close the Settings app and restart your device as iOS clears cached data and does other system optimizations when you turn your device off and on. Then follow these steps, including contacting your email service provider.
If you need to set up your email account manually, make sure that you know the email settings for your account. If you don’t know them, you can look them up or contact your email provider. Then follow these steps:
- Go to Settings > Accounts & Passwords and tap Add Account. If you're using iOS 10.3.3 or earlier, go to Settings > Mail > Accounts and tap Add Account.
- Tap Other, then tap Add Mail Account.
- Enter your name, email address, password, and a description for your account.
- Tap Next. Mail will try to find the email settings and finish your account setup. If Mail finds your email settings, tap Done to complete your account setup.
If Mail can't find your email settings, then you need to enter them manually. Tap Next, then follow these steps:
- Choose IMAP or POP for your new account. If you aren’t sure which one to choose, contact your email provider.
- Enter the information for Incoming Mail Server and Outgoing Mail Server. Then tap Next. If you don't have this information, try to look it up or contact your email provider.
- If your email settings are correct, tap Save to finish. If the email settings are incorrect, you'll be asked to edit them.
If you still can't set up your email account or save your email settings, contact your email provider.
Force an app to close on your iPhone, iPad, or iPod touch
Restart your iPhone, iPad, or iPod touch
Set up an email account on your iPhone, iPad, or iPod touch - Apple Support