Spam mailbox problem

Receiving advertising mails with my full name as header, and clicking on the from link gives my Contacts page with my full name. I have two iPads and an iMac. How and in what order do I change passwords and fix this, please?

I assume this is spam. My email was hacked recently and I changed Apple passwords and thought it was fixed.

I have two other mail accounts, one I have never accessed and a hotmail I have not used for,years so assume the mac mail is the problem.

Thanks.