Someone is running a spear phishing attack against my tiny business, which feels unexpected given the size of my organization (just me).
Could you recommend some simple ways I can stop the attack? It involves extremely well-designed emails from various compromised email addresses that impersonate the SendGrid system and use very plausible messages.
My main concern is that this could evolve into something more sinister. I don't mind blocking all emails containing "SendGrid," but I would rather do something that could make those people move on and not come back.
Thanks so much!