Gmail Outbound Sending Limits

Here is the sending limits of Google: http://mail.google.com/support/bin/answer.py?answer=22839

In an effort to fight spam and prevent abuse, Google will temporarily disable your account if you send messages to more than 500 recipients or if you send a large number of undeliverable messages. If you use a POP1 or IMAP2 client (Microsoft Outlook or Apple Mail, e.g.), you may only send a message to 100 people at a time. Your account should be re-enabled within 24 hours.