Gmail imposes a daily 500 recipient quota for sending emails. If you send through their POP/IMAP interface that quota is only 100 recipients per day.
What is the sending quota for sending an email on a gmail account using the google app engine? Would it follow the POP/IMAP limit or the standard gmail limit?
Here is all the official gmail quota information I found: http://mail.google.com/support/bin/answer.py?hl=en&answer=22839
The answer depends on how you decide to send the email.
- Are you using the built in App Engine mailing API? If so you, can send lots and lots of emails (see amir's answer).
- Are you sending your mail through Gmail's SMTP server? ( I assume you meant SMTP when you said POP, as POP is only for reading email) If so, the limit is 100, as you state.
- Is your app connecting to gmail through http and pretending to be a human using the normal interface? Then the 500 limit would apply.
When using app engine api to send emails (and you have billing enabled), you can send 4900 emails/minute. See the quotas on this page: http://code.google.com/appengine/docs/quotas.html#Mail
Apparently, Google has changed the quota for email recently. The limit has gone down to 100 emails per day, with no option to buy more. Google advises to use SendGrid to send more email. If anyone could post Java code to use sendgrid, that would be helpful, as Google's documentation is lacking, as usual. Edit: There is documentation for Java. I have not tried this yet.
来源：https://stackoverflow.com/questions/4882969/gmail-send-quota-when-sending-using-google-app-engine