I am using Outlook.com and a specific email that I sent on 15th January and yesterday is being duplicated in my Sent Folder.   It drops in 4 times at a given time.    And does this when I have sent an email to somebody.  It then drops in the old message again a few minutes later.  Is this a bug?  And how can I stop this from happening as I have to keep on deleting the messages?

I recently got a new Samsung phone where I am sending emails from Outlook so I'm not sure if this is the problem... wrong app using or something.

Thanks.