As any salesperson, PR rep or entrepreneur can tell you, the rate at which people open and respond to your emails can be the difference between accelerating your career and the pit of despair. 

No wonder we all spend so much time obsessing about subject lines, exact phrasings and crafting the perfect ask. But according to research from Boomerang, an email software company, there's one part of your messages you're probably not putting enough thought into -- your closing. 

Most of us slap a pleasant-sounding "Best" or "Regards" on the end of our emails and call it a day. But when Boomerang trawled through 350,000 emails to see how particular closings impact whether a message gets a reply, they discovered how you sign off matters a surprising amount. In fact, simply ending your email with an expression of gratitude can dramatically increase the likelihood of getting a reply.