If you are not able to send or receive emails in the Mail app on your iOS device, know what to do.
You can try the steps given below from emailstechnicalsupport.com:
Please check if your device has a cellular-data or Wi-Fi Internet connection, go to Safari and open a webpage, like www.apple.com.
Check the Outbox for emails which has not been sent-
If you see a message that your email wasn’t sent, then that email goes to your Outbox. Check your Outbox and try to send the email again.
Check your email address and password
If Mail asks you to enter a password for your email account, your password should be correct. To check your email address and password, sign in to your email provider's website.
Check for your settings
When you set up email account on your device, iOS automatically uses the correct account settings for many email providers.
To have surety that your account settings are correct, compare the settings in the Mail app with the settings for your email account.
Contact to your email provider or system administrator
You can either check your email provider or check their status webpage to understand if there's a service downtime.
Contact your email provider or system administrator if you have turned on either any security feature or restrictions, like two-step verification, for your email account. You may require a special password or required to request authorization from your email provider to send and receive email on your device.
Check your email account settings by the help of your email service provider or system administrator to make sure that they're correct.
Remove your email account and set it up again
- In your system, sign in to your email service provider’s website. Confirm that all of your email is there or be sure that your email is saved at another place other than your iOS device.
- On your iOS device, go to Settings > Accounts & Passwords.
- Tap the email account that you want to remove.
- Tap Delete Account.
- Add your account again.