Email question

Hello,

Not sure where to post this but I hope I can get some advise/info. Today I opened my Microsoft outlook email account on IE as normal and was looking in my Junk folder when I noticed that  apparently I had sent myself an email with an attachment a couple of days ago. It had come from my exact same email address and name of the account I was accessing, same format/spelling etc...I opened the email and disabled the smart screen filter just to see what it was and it had a zip file attachment.  Of course I DID NOT open the attachment or download the zip (just viewed the email without the smart screen filter) and left it in the junk filter (which I then emptied). Problem is I know I didn't send myself an email and when I look at my sent items it does not show that any email addressed back to myself was sent on the date of this particular email. Looking at my recent actions also shows nothing out of the ordinary. 

Does anybody have any insight into this? Was my mailbox hacked? Also, by merely opening the email without the smart screen filter did I endanger my computer or email account? Out off an abundance of caution I promptly changed the password on my email accounts.

Any help/advice would be greatly appreciated.

 

Thanks.