Mail not opening

[iOCMark]

Anyone experiencing problems opening their Mail program?

Was using Mail most of the day today; all of a sudden it stopped; had to force quit.

Now it will not open at all. Keep having to force quit out.

Tried restarting; no luck.

Any advice would be very much appreciated.

 

[AMCarter3]

I just had that happen on our Macbook AIR. Mail has been working fine since upgrading to Yosemite last week. Today, it stopped opening. It tries to open, but hangs and I have to Force Quit it.