The IMAP and GMAIL REST APIs have their own quota, the Gmail API is subject to a daily usage limit, which applies to all requests made from your application. For daily use, it has 1,000,000,000 quotas per day and 250 quotas per user speed limit.
For an IMAP mail client, the maximum number of recipients allowed for each eamil is 500 receipts.
To view usage restrictions for your project or request a quota increase, open the API library on the Developer Console.
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