Exchange Online - disable rejection/expiration notice

Question

Hi,

To block malicious mails, our Exchange Online server has a message rule that forwards any mail with a .htm, .html attachment to us (system administrators) for approval. The rule works, we regularly get requests from the mailserver to either approve or deny certain mails that contain these attachments. About 90% of these mails is malicious and should not go through.

We don't want the assholes sending these mails obtaining any information about our company or what was what done with the mails they sent, yet when we deny the mail by clicking the deny button a formal rejection notice is mailed back to the sender. The same goes for when we let it expire and don't take action at all, in that case a formal expiration notice is sent back to the sender. Is there any way to stop Exchange Online from sending these notifications? Like I said, we don't want to provide any info to the phishers/attackers sending these mails.

Thanks in advance

Answer 1

Honestly, if 90% are malicious, I would just change the rule to either send everything to the quarantine and release later if needed or simply delete the message with no NDR with the rule.