Unknown person joining my meeting

[Linzhess]

I received an email message that "so and so" had joined my meeting.... the meeting was a recurring one and the individual had joined the meeting 2 months in the future.  I signed on and started the meeting - no one was there, but  how can this happen, and further.. how can a person join a meeting two months in advance?  Does it indicate that someone is using a recurring meeting for their own purposes?  or that someone accidentally joined the meeting and somehow the date was two months away (it is a recurring meeting).  I am confused and just want to be sure that no one is able to use my scheduled meetings independent of me.  

[Buttercup]

Once a meeting has been scheduled, it is available for people to enter.  If you're concerned regarding some one using your scheduled meetings without your permission, please consider using passcode, and disabling or limiting the "join before host" option.