Hello Vishal,Initially, you can follow the below link for content matching criteria of Cisco Secure email DLPhttps://www.cisco.com/c/en/us/td/docs/security/esa/esa13-5-1/user_guide/b_ESA_Admin_Guide_ces_13-7/b_ESA_Admin_Guide_12_1_chapter_010010.html...

Hi tipper, Thanks for your post.  I have some queries to point out your issue. How have you ready your cer as pkcs#12 and How you ensure that your cert was loads successfully?  And, if possible, then please share/attached the screenshot of the error ...