For several years, I have noticed other people using my domain for their emails. How is this possible? My domain is terramar.co. Every few months, I'll see a flurry of emails from various recipients and senders with emails like firstname.lastname@example.org. They are different every time. I'd like to put a stop to it somehow. But I don't how they are able to use my domain to begin with. Any thoughts?
Any email address can be put in the from field -- it is just an setting. I could send an email looking like anyone I wanted right now just by changing what displays in the from field of my software.
Most likely spammers/bots are just auto-filling into the from field. I get spam emails from my domains too -- it doesn't mean they are going through my servers or that a human being is actually using the address.
You could track where the emails originate and report them but that is easier said than done. Scanning the headers at Spamcop.net can help you determine where these are originating form if you want to pursue and report.
I have the same problem, only thing is that it seems like people even have their apple account like "email@example.com" so I am getting their billing correspondence. I have also have received other emails that look like legitimate conversations, in my catch-all account.
I am not sure if I should be concerned or if this is just a nuisance?