Steps to follow If you can’t send or receive emails in the Mail app on your iOS device

1. Before you begin

          First delete or change your email account settings, previously downloaded email might be removed from your iOS device

2.  Make sure that your device can connect to the Internet

          Device has a cellular-data or Wi-Fi Internet connection, go to Safari and open a webpage, like www.apple.com.
 

3. Check the Outbox for unsent emails

           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
 

4. Check your email address and password

           Enter a password for your email account, make sure that your password is correct. To check your email address and password, sign in to your email provider's website.
 

5. Check your settings
   Go to Settings > Accounts & Passwords and tap your email account.
   Tap your email address next to Account to see the account information, such as the incoming and outgoing mail servers.