mail icon doesn't let me send emails
I've had my macbook a few years now and everything has been working fine, until a few days/weeks ago. My mail icon on my taskbar doesn't let me send emails any more. it receives emails and has always worked in the past, but now I have to log in to the internet and google to send emails, which has limited abilities compared to the mail icon. I have recently updated my operating system to Yosemite, any ideas ?
MacBook Pro, OS X Yosemite (10.10)