what you have done is perfect buddy
just we need to add two activities inside the THEN part of IF condition in your current process workflow
and the first activity is assign activity with which you can edit the mail body and assign that to a string variable named strinput
then the second one to be used is REPLY TO OUTLOOK MAIL activity which is what is used to reply back to the mail we want where we can mention the string variable strinput that has the changed mail body
Here I have to read entire mail in HTML format and then have to edit the email so the format remains same.
As i am new to UI path will you please elaborate the same, how it can be done ?