We have splitted away from our parent company which hosted our former mailboxes under our old e-mail address domain (e.g. olddomain.com). During a period of time, we have an e-mail forwarding from olddomain.com to newdomain.com.
However, as this forwarding is already in effect and we have migrated the content of the mailboxes we wish to delete the content of these mailboxes.
How can we do this centrally in a easy and effective way?
It's important that we do not delete the e-mail forwarding (which is done by "Mail flow"), but only the data (e-mails, calendar and contacts).