Emails Stopped

Hi,

I have a client who has been using LEM for about 4-5 months now, and within the last few weeks (without any changes to the system), Email alerts have stopped being sent out.  They have tested the Email setup successfully in LEM appliance, but the alerts aren't coming.  I haven't had the chance to login to have a look, but any ideas on things to look into?

Thanks

MG2