Error writing to email body, by Outlook

I can write a text capture by OCL and send it by Exchange. But when I want to send it to “Reply all” I can’t do it by exchange (because there is no such activity). Then I click open mail. Then click on “Reply all”. And I use “Write to” to write in the body of the email. There I put a variable that in SendMessage via Exchange works fine, but here it gives the message:
“Syntax error in special keys. Invalid special key action found at text position: 2. "

Can someone help me?
Thank you