Mac Mail hacked FIVE times!

Question

I've had the same e-mail address for over twelve years and I'd never been hacked (or whatever it's called when everyone in your address book receives spam from you) until six months ago, when I bought a Macbook Pro and started using Mac Mail. Since then, my e-mail has been hacked five times. Each time, I've immediately changed my password to at least twenty random symbols, numbers, and upper and lowercase letters. It makes no difference; the e-mail address I use with Mac Mail still spams all and sundry.
What is going on? Is the culprit the Mac Mail program or could the computer itself be compromised? I bought the Mac with Windows without Outlook because Mac Mail seemed like a comparable substitute. Now I'm tempted to purchase the Outlook add-on to see if I still get hacked using it. What else can I do? No other family members (all on Dells or Acers) are having this problem and Verizon says the connection is secure. Any ideas are appreciated!

Answer 1

when everyone in your address book receives spam from you
This is most often caused by someone else's computer getting hacked, getting their Address Book compromised, and disclosing your email Address.
The spammer then sends FAKE emails, tagged with your email address as the sender.
In this case, NOTHING about your Mac, or your email account has been compromised at all. Someone's compromised computer is sending spam and inserting your email address in the Sender field.
I had this experience, and it turned out to be a computer of someone I had bought something from on eBay, years before, had their computer hacked. My address was in their Address Book, so his computer sent out emails with my name as Sender.
If you can get a receiver to show full headers, then cut-and-paste that text into a new email and send it to you, that can be analyzed to determine the actual sender.
Or a computer-savvy friend can look at the full headers and see who the actual sender is.