after each change of such important settings it is nice do perform a real test if your server is not a "open relay".
There are many web sites where you can trigger such a test for free.Search for "open relay test" on the web or try this one:
Look in you log database in the mail routing events. You should be able to find out from where all the e-mails came from. Post some lines from this help in case that you cant figure it out.