user exit or badi on TCODE : ME21N purchase order output screen

hi Good day,

i have requirement from business to auto fax and email when user click on ENTER using TCODE : ME21N or ME22n, at location

1.TCODE : ME21N.

2. application tool bar : Click on MESSAGES button

3. New screen opens up :

4. here user inputs ex : zfax and selects FAX from dropdown

5. when user click on ENTER he wants the POP-UP  (the same pop-up when you click on COMMUNICATION METHOD button).

i have searched for the exits and badis but non of them trigger at this point.

can anyone shed some light on it please?

thank you,

jacob.