If Gmail is returning your email messages with an error saying you've reached the limit for sending email, here are reasons why that happens and what you can do to avoid Gmail from bouncing your emails

Gmail has certain limits in place and you only send or receive a limited number of emails per day. The daily limits are 2000 email messages for Google Workspace accounts and 500 for consumer Gmail accounts.

It is important to know that Gmail sending limits are per user and thus shared between all email clients, Google add-ons, SMTP clients and other apps that could be sending emails through your Gmail account.

For instance, if you have sent 300 emails through the Gmail website, 50 emails through Microsoft Outlook linked to your Gmail account via IMAP or POP, and another 100 messages through an email alias on a different domain, the maximum number of emails you can send through the Gmail Mail Merge (or any other Google add-on) will be just 50 in the 24 hour period.

If you exceed the sending limit, you’ll get an error message - like “you’ve reached a Gmail limit for sending email” or “Oops.. the system encountered a problem” - and Gmail may sometimes temporarily block you from sending new messages. The limits are not applied at any set time of the day and the user may have to wait up to 24 hours before the limits are reset automatically.

[*] The daily sending limit is even lower - 100 total recipients per day - if you are using Microsoft Exchange or any non-Google SMTP service for routing messages through Gmail email servers.

Email Bounced - Your Message Was Not Sent

You have reached a limit for sending mail. Your message was not sent.

If you get a bounced email from nobody@gmail.com - with the message saying “An error occurred, your message was not sent” or “You have reached a limit for sending email, your message was not sent” - there are several reason why that may happen:

1. It may indicate that you have reached the Gmail sending limit for the day. You could be sending emails through IMAP or POP email clients (Apple Mail, Outlook), or you are sending emails from different aliases or you are using multiple add-ons for sending emails.

2. Your messages can bounce if you are sending many emails to non-existent email addresses. It is thus important to clean up your mailing lists and remove invalid email addresses before running another Mail Merge campaign.

3. Gmail can also limit your email sending capability temporarily if 10 or more recipients have hit the “Report Spam” button for your email messages. Thus, you should not send unsolicited emails to people who have never agreed to receive emails from your address.

4. Gmail can also reject your emails if their algorithms classify your email message as spam. This happens when you have words that are seen as spam in the message body, or if you have links pointing to unknown websites, or if you have a large number of recipients in the CC or BCC list or you may have attachment that are seen as suspicious.

There’s no workaround to this problem and you’ll have to wait until Gmail resets your email quota. After the quota is reset, you can resend the message to the same recipients and they should be delivered as normal.

Best Practices - Improve Gmail Deliverability

To avoid the Gmail spam filter and improve your chances of your emails landing in the primary folder of the recipient’s inbox:

1. Send emails to valid email addresses only.
2. Get permission from your recipients before sending them emails (opt-in).
3. Clean your email database and remove email addresses that have bounced or unsubscribed.
4. Add an unsubscribe link in email to let users opt out of your mailing lists.
5. If you have GSuite (Google Workspace) domain, make sure that the SPF and DKIM records are properly setup for the domain.
6. Some spam filters may be triggered by the content of the email message like the subject, the text in the email body, the images or the links in your email. Test your campaign with a small set of recipients.
7. Avoid copy-pasting newsletter designs from Microsoft Word, write emails in simple HTML and CSS.
8. Ask your recipients to add your email address as a contact.
9. Disable tracking for email opens and link clicks.
10. If you have a new GSuite (Google Workspace) account, Google will put your email account in trial mode and your daily email sending limit is increased after a few billing cycles.