Ok now, I am having stuff sent to my email from someone that apparently has the same email address as this alias address I created?

I got a confirmation from Domino's pizza, in a different state, for this person, and she does have the same name as mine and is apparently using this email address.  Question, is she also getting MY email in HER inbox??  How do I figure out if this is her just maybe listing the wrong email address, or if this email address is being allowed to be assigned to us both?

I can't figure out how to actually open a support ticket with Outlook to get them to investigate, this is the closest thing I have found.  Based on some of the questions I have read, I am afraid they are severely lacking in support altogether and may not even address this issue I am having.

Any help would be appreciated! 

Thanks.