What does the grey arrow mean next to my sent email?

[hwheatley]

Hi, I have a Moto X with Email app synced to my outlook account. I noticed today that in the sent emails folder, one of the emails has a dotted grey arrow symbol to the left of the the To: field. None of the other sent emails have this. Does anyone know what this means? This is a suspicious email that I don't think I sent (unless by accident) so I'd like to know what the arrow means!
Thanks

 

[ManiacJoe]

What direction is the arrow pointing?
Often times, up and down can indicate hi and lo priorities.
That said, the "help" section of your email app should explain the icons used.