how can I stop my friend’s emails come to my email box ?

I receive my friend and her husband's email.  How can I stop the emails that do not belong to me STOP!  Some of the emails are not welcomed.

Some of the emails contain my friend's travel itinerary.  Some other emails contain personal credit card account information. 

The worse feeling is that, how do I know my friend and her husband are receiving my personal information or other's email.

I have tried to contact my friend and make her understand the situation, however, I am still getting some of her / her husband's emails.  I wish to continue with Hotmail, however, I don't want to change what I have on the account for many years. 

Please help me correct this.  Thank you.