How to amend delivered alerts notification to have customized message?

Hi All,

We have a required to have custom message when a job requisition is suspended.

Someting like this "Requisition will automatically be cancelled 3 weeks from now, <add 21 days from todays date>"

I see only one expression to display system date - ${AlertUtils.getSysdate()}

Any idea how can we add 21 days to cuttent date. I did try this but its not working - ${AlertUtils.getSysdate()+21}