# SMTP: 550 5.4.5 Daily user sending quota exceeded (Gmail)

**Code:** `550 5.4.5 Daily user sending quota exceeded` · **Category:** Email / SMTP · **Seen on:** SMTP

The Gmail or Google Workspace account reached its 24-hour sending limit, so it stops accepting outgoing mail until the limit resets.

## Meaning

Gmail limits are about 500 recipients per day for consumer accounts and 2,000 for Workspace (SMTP relay has separate limits). Reaching it blocks sending for up to 24 hours. Use an ESP for bulk mail, reduce recipients, or use the Workspace SMTP relay service.

## Common causes

- Bulk mailing from a normal mailbox
- Script retrying in a loop
- Newsletter or notification app using Gmail SMTP
- Compromised account sending spam
- Many Bcc recipients counted separately

## Quick fix

1. Stop sending and wait up to 24 hours
2. Move bulk and transactional mail to SES, SendGrid or Mailgun
3. Use fewer recipients per message and review the account for abuse

## Detailed fix by platform

### Linux

1. Count what your app sends per day: `grep -c "status=sent" /var/log/mail.log` (Postfix relay setups)

## How to diagnose

1. **Volume** — Recipients in last 24 hours?
2. **Source** — Script or newsletter tool?
3. **Security** — Unexpected sending?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/email/gmail-5-4-5-daily-limit-exceeded)