I have a sheet where we track department metrics in Google Sheets. I am trying to get it to email when a metric changes. I am using counta (in range P2) to monitor if a new me
Cells that change because of a formula do not qualify as an 'edit' to trigger the onEdit function. You should either monitor the source cell(s) (if they are edited manually) or the second alternative is to have a function running under a trigger that runs every minute (or whatever frequency you like) and send out the email. The function you've written looks good to be run under a trigger.