Change content of send e-mails

[espresso]

Hello,

I try to change the text message of e-mails send from my users to customers, e.g. I want to add a parameter to links. I tried to change the $Param{Body} variable in /opt/otrs/Kernel/System/Ticket/Article/Backend/MIMEBase.pm, but it does not work as suggested as it also changes all the links in other articles like notes and incoming e-mails. Perhaps checking the type of article may be a solution, but I am wondering if this is the right way to do it or if there is a much better way to change the body of an e-mail before sending. If someone has suggestions about this it would be very kind if you could post it here.