Gmail "550 5.4.5 Daily user sending limit exceeded": what to do

What it means

This is not a problem with the recipient. Your own Gmail or Google Workspace account sent more email in 24 hours than Google allows, so Google stops it from sending more for a while. The message usually looks like one of these:

550 5.4.5 Daily user sending limit exceeded. For more information on Gmail
sending limits go to https://support.google.com/a/answer/166852

550 5.4.5 Daily SMTP relay limit exceeded for customer.

In Gmail itself you may instead see "You have reached a limit for sending mail". The first message concerns one user account. The second concerns the Google Workspace SMTP relay service, used by printers, websites or applications sending through Google.

Why it happens

Google limits how many messages and recipients one account can send per day. The limits change over time, but roughly:

• Free Gmail accounts: about 500 recipients per day.
• Google Workspace: about 2,000 messages per user per day, with lower limits during a trial and for external recipients in a single message.
• SMTP relay: a separate limit per user and per organization, counted in recipients.

Common reasons for reaching them:

• Sending a newsletter or mass mailing from a normal mailbox.
• A website, CRM or script using your Gmail account to send many emails.
• A compromised account sending spam.
• Many bounces to invalid addresses, which can also lower the limit or cause a suspension.

How to check

• Look at your Sent folder and, for Workspace, the email log search in the Google Admin console, to see what was sent and by which tool.
• Check account security. Look for unknown devices or app passwords in your Google account security page. Unexplained sends mean you should change the password now.
• For other tools, once you move bulk sending elsewhere, send a test email from that tool to the unique address on the Delivmail home page (/) and check that SPF, DKIM and DMARC pass for your domain.

How to fix it

1. Wait. The limit is on a rolling 24-hour window. Sending usually comes back within 24 hours. Trying to send more during this time does not help.
2. Secure the account if you did not send these emails: change the password, enable two-step verification and remove unknown app passwords.
3. Move bulk email to a dedicated email service. Newsletters, announcements and large notification volumes belong on an email marketing or transactional email service, not a personal mailbox.
4. Authenticate that new service for your domain: add it to your single SPF record, publish its DKIM key, and keep one DMARC record for the domain.
5. For the SMTP relay limit, the Workspace administrator should check which device or application is using the relay, spread its sending over time, or move it to a dedicated service.
6. Clean your address lists to avoid bounces, which count against you.

Check that it is fixed

After the waiting period, send one normal email from the Gmail or Workspace account. If it goes out, the limit has reset. For the new bulk tool, send a test to a new Delivmail address and confirm the report shows authentication passing, then resend your campaign from that tool rather than from the mailbox.