That's easy.
Enable email modification in the forum manager and fill out the "reply address" as the admin's email address.
Disable the scheduled task for Email Integration in the scheduled task manager.
Then you can go to Languages & Phrases -> Search in Phrases -> searching for ei_notify in the variables and you'll see all the phrases for the emails. Then you can modify those to your liking.
I do NOT suggest anyone change any of these phrases unless they will be disabling incoming mail!!!
The regex in the scheduled task rely on specific layouts of the -=-=-=-= lines in the emails to correctly parse and interpret the incoming emails!