Google has a number of sending limits in place to prevent abuse:
- Users can send mail to 2,000 external recipients per day
- Google Apps for Business and Education
- Google Apps (free) is limited to 500 external recipients per day
An individual message can be sent to a maximum of 500 recipients at one time.
Note: No limits to number of messages sent to internal recipients.
For more information on the sending limits, kindly visit: http://support.google.com/a/bin/answer.py?hl=en&answer=166852
Tips to handle sending limits:
- Send same message from multiple users
- 2 users can send same message to 4,000 external recipients
- Stagger messages over 2 days
- Create a group for mass mailings
- Message sent to a groups counts as 1 message
- Consider using Google Groups - http://groups.google.com