SSL warning - LAN access exchange

friends.. i guess this would be easy but i am not able to put this in picture..

i have ex 2013 SP1 / 2010 (Two different clients) running.. and a is good. users access their exchange over a LAN network.. during LAN access when they start the outlook they get the SSL warning saying the server name and SSL name is different and which is true also.. as my server name is abc.client1.localwhere as SSL is mail.client1.com please advise what piece i am missing and the concept knowledge also.

thanks for the time and replies..