Iphone scam/warning

Try a forced restart - After shutting down all open apps using the app switcher - invoked by quick double press of the home button and swiping up on each app till it flies off the screen.

Hold the sleep/wake and home buttons down together till you see  logo - then release and allow normal boot up

Your phone has not been compromised as long as you didn't respond in any way and your phone is not jail broken. Try closing the mail app completely and force restart the phone.

Press the Home button two times quickly. You'll see small previews of your recently used apps. Swipe left to find the app you want to close. Swipe up on the app's preview to close it.

To force restart your device, press and hold both the l/Wake and Home buttons for at least ten seconds, until you see the Apple logo.

If that didn't fix it, Reset all settings. Perhaps a setting got corrupted when you updated. You will not lose any data, but all of the device settings will have to be entered in the settings app again including WiFi network passwords. Settings>General>Reset>Reset all Settings.

If you continue to have the issue and it is a bother -

Backup to iTunes

Then restore as NEW using iTunes

Do not restore the backup

See if the problem resolves

If it does - restore backup - if the problem returns - then chances are your content is corrupted somehow

Did you also look into

Settings > Safari > Advanced > Website Data > ???

Delete that e-mail from your Mail app

That website maybe compromised, should be avoided.

1. Double tap Home button, swipe up Safari from multitask screen to delete Safari

2. Do in Settings > Safari > Clear History and Website Data

3. Do a force restart: http://support.apple.com/en-us/HT201559

Check your Safari Favourites