how to make mail add ins for office365 and outlook.com

Question

Hello,

 

 

i made a add ins for  exchange server  and office365. its working perfectly.but i wont mandate on send  button..so i wont to work on send button..

 

 

eg.. we press send button so before send the mail i wont to do something than i  wont to  send the mail.

 

 

any idea share me quickly .its very urgent...