Why is my Email Limit only 400 in Gmail

I am using the Mail Merge with Attachments addon for sending emails via Google Sheets. My premium plan should allow me to send 1500 emails daily, but I am currently limited to sending 400 emails per day. Why is my quota not 1500 in Gmail?

There could be several reasons by your email-sending quota is limited to 400 emails per day.

Reason 1.

You may have activated the license on a free @gmail.com or @googlemail.com account. Please note that Google offers a higher email quota to paid Google Workspace accounts only.

If you have a Google Workspace account, you may contact support and request to transfer the license from your Gmail to your Google Workspace account.

Reason 2.

If you have a Google Workspace account and yet your quota is not 1500, it is likely that you have recently created a Workspace account with Google.

Google imposes some restrictions on new Workspace accounts. Once these requirements are satisfied, Google will automatically remove the trial status from your Workspace account, potentially increasing your email quota.

Please contact Google Support directly for help on how to move your account out of trial mode.