OlivawR: I don't like it. It's a catch-all email setup. While I have no idea if spammers do bother with catch-all email addresses, I still prefer to create an weird name like g_man@mydomain (instead of google@mydomain) address.
If you are ok with checking 126 email addresses, then of course you are just fine. If you only want to check one address though, yet still know who leaked your email, the regular expression may be better.
So, to clarify the example.
You have the man@mydomain email address. For google, you sign up with google.man@mydomain, for gog you sign up with gog.man@mydomain, for amazon you sign up with amazon.man@mydomain and so on. All the mails will end up in the man@mydomain address, though they will have a different to: field.
Yes, this does mean that you may also get mail addressed to any.man@mydomain, though I'm not sure if such an address would be created instead of harvested.
But as I said, whatever works for you :)