I also have my own domain name and whenever I sign up for anything (if I really have to give them an email address) I will make it: companyxy.net@mydomainname.m

I also have my own domain name and whenever I sign up for anything (if I really have to give them an email address) I will make it: companyxy.net@mydomainname.me and indeed, whenever I receive a spam email I know what company sold (or leaked) my email address, because it is right there.....