[otrs] suppress automatic notification of agent about mail from that same agent

Hi, some of my collegues (OTRS agents) prefer to work on tickets using their prefered mail client instead of the OTRS framework. When doing so, they send a carbon copy to the otrs mail address. Thus their reply is added to the ticket history. OTRS sees this mail (the CC) as an external mail (which it is). Consequently it notifies any involved agent about this incoming external mail. For truely external mails, this notification is exactly what the collegues want. Is it possible to ask OTRS to suppress the notification in case the sender of the external mail and the recipient of the notification are identical? Thanks for any hints, Julius