How to configure automatic mail merge of same subject

Hi All,

I have used RT 3.8.7 Ver. My concern is that how to configure automatic mail
merge of same subject and how to configure when a user send a mail on
ticketing system the system can not create a ticket against the user mail
and some subject.

Bijendera Kumar
IT Team
Travel Boutique Online
Ext:1064,1105
Tel: 91 1244998999
Mob: 91 9811449512
Email:bijendera@travelboutiqueonline.com