Sending Limits

In order to prevent spam, Google will temporarily disable accounts that send a lot of email in a short time.

It's important to be aware of Google's sending limits:

• Messages per day (2,000)
• Recipients per message (2,000/ 500 external)
• Total recipients per day (10,000)
• External and unique recipients per day (3,000)

For alternatives, consider sending emails through Google Groups, Broadcast Email Messaging, or LISTSERV.

Bandwidth/Sync Limits

Similarly, Google Apps accounts also have limits on bandwidth and sync: "Certain activities that transfer large amounts of data in a short period of time, like synchronizing a Gmail account to a mobile phone or mail client, can cause an account to reach the bandwidth limit." If you're using Google Apps email to send many large files, a better tool that will help you avoid these bandwidth limits is Google Drive sharing.

See Bandwidth limits and Sync limits for more information.