To keep Gmail systems healthy and your accounts safe, Google limits the amount of mail one user can send. Limits restrict the number of messages sent per day and the number of recipients per message.
- Free Gmail and trial Google Apps accounts have sending limit of 500 messages per day.
- Paid Google Apps accounts have the limit of 2000 messages per day.
In order to comply with above restrictions, cloudHQ will ensure not to send more than 450 emails per day for free accounts and 1800 emails per day for paid Google Apps accounts. So if your email campaign has more than 900 emails and you are using free Gmail account it might take ~2 full days to email everybody.
If you exceed a Google email sending limit, you will see an error message, such as:
- You have reached a limit for sending email.
- You reached a Gmail sending limit.
- You exceeded the maximum recipients.
After reaching one of these limits, you will not be able to send new messages for up to 24 hours. However, you will still be able to access your Gmail account and receive incoming email. After this suspension period, sending limits are automatically reset and the user can resume sending mail.
Here is the explanation of Google Apps Gmail sending limits:
https://support.google.com/a/answer/166852 (see Daily sending limit section)