IPhone 5s :: Not Receiving Emails But Can Send Them

My Fiance and I upgraded our phones yesterday. We both now have the iPhone 5s. Everything from the iCloud transferred over great. My phone is working perfectly. My fiancé's phone however is having problems with his yahoo email account. All of his sent email is showing up, and he can send them out; however, nothing is showing up in his inbox and he cannot receive any emails on his phone. We compared mine to his and every thing is set up the same, however we cannot figure out why he is not receiving emails.