Unable to send emails from gmail account on iOS 7.1
This appears to be a problem with Google's SMTP servers, affecting all clients on all platforms (excluding web) and preventing the sending of email.

This has now been fixed:


  This issue is now resolved. Thanks again for reporting this to us and for your continued patience while we worked to resolve it!


https://productforums.google.com/d/msg/gmail/xChsjMRFCUc/-YbEFrt5ODUJ



At the time of writing, Google are aware of this and are working to fix it.


  Thanks for providing information about this issue - we're actively investigating and I will post back here when I have more information.


https://productforums.google.com/forum/#!starred/gmail/xChsjMRFCUc