Hello all, I keep getting mails purporting to be from my organization which is fraudulent and I am certain its not from my organization its an attack . The problem is every time we block the originating IP they will change it and re-send. Last week we had about 80,000 of those mails sent. The mails appears to be from withing our domain abc@ourdomain.com. We believe the reason we are getting it is when the attacker sends the malicious email upon reply it delivers to us since thereby misleading a victim to make it look like we sent it. Please assists if possible.
I have tightened the mail inbound rules but still the problem persists. Its a Lotus Domino 8.5 environment.