cannot or failed to verify outgoing smtp for gmail account

Contact your email provider or system administrator

1. Contact your email provider or check their status webpage to see if there's a service outage.
2. Ask your email provider or system administrator if you turned on any security features or restrictions, like two-step verification, for your email account. You might need a special password or need to request authorization from your email provider to send and receive email on your device.
3. Check your email account settings with your email provider or system administrator to make sure that they're correct.

Remove your email account and set it up again

1. On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than your iOS device.
2. On your iOS device, go to Settings > Accounts & Passwords.
3. Tap the email account that you want to remove.
4. Tap Delete Account.
5. Add your account again.