iPhone 4S battery and emails

Hi,



Re: Iphone 4S. iOS 6.1.3



Few issues:

Battery is draining fast (7 hours on standby)

I am receiving emails on yahoo account but not on work (exchange)

I cant send emails from any account



So I backed up my iPhone and then reset (erase all contents and setting). Once restarted, it worked fine ie battery was ok and I was able to send/receive emails.



Later I connected to my iTunes and restored the backed up data.



Now I am facing the same problems again (battery draining and no emails).



So now I know there is nothing wrong with the phone in regards to hardware but may be some settings or applications are causing this problem.



Any advise please?



Thank you in advance