Unable to add exchange email account on LG G3 with Android 4.4.2
Login to your email on the Web.  Check Settings > Options . There might be an option such as "Connect Devices &amp; Apps with POP".  Ensure that this is set to Enable.

I had the same issue when setting up a Windows Live email on an LG G3.  Once the POP setting was Enabled, the email email account set up worked fine.

Good Luck.