Email scams from personal email domain?

How is it able that I received email from unknown user with my own register email domain? eg. my domain is @abc123.com and the user is something@abc123.com.
Email scams from personal email domain?
A scam is different from spam. Spam is unwanted or unsolicited email, which is apparently what you got. A scam is an attempt to fool someone into doing something that is stupid, foolish or dangerous.
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