Error: email quota exceeded

Hi folks,

After several hours of thrashing while trying to get my app to work right, I received an error that my email quota was exceeded.  (Yes I am debugging the part that sends emails.)  I can find no information documenting what this quota is and what its parameters are.  I am currently running in the cloud trial.  Is this limit specific to that?  Does it reset? or once exceeded does it stay in place?  Any help will be appreciated.

Thanks in advance,
Carlene