The following 2 links should cover most of the limits:

http://www.google.com/support/a/bin/answer.py?answer=59797&query=limit&topic=&type=
http://www.labnol.org/internet/email/gmail-daily-limit-sending-bulk-email/2191/


>Yes I am sure it got locked out because I sent over 1000 emails through my monitor application in a couple of weeks. I am just having a hard time finding documentation from GMail about this.