550 5.4.5 Daily user sending quota exceeded Email / SMTP Origin: Network Last updated 4 Nov 2026

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

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

Exact message you may see 550 5.4.5 Daily user sending quota exceededDaily sending quota exceeded550-5.4.5 Daily user sending limit exceeded5.4.5 Daily sending quota exceededGmail daily limit exceeded SMTP
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Seen on: SMTP

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?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Network. Errors that are often confused with or caused by this one (click to open):

421 4.7.0 Try again later (rate limited) — SMTP: 421 4.7.0 Our system has detected an unusual rate of unsolicited mail originating from your IP address. Mail sent from your IP address has been temporarily rate limited (Email / SMTP)421 4.7.0 Try again l…450 4.7.1 Greylisted, please try again later — SMTP: 450 4.7.1 <user@example.com>: Recipient address rejected: Greylisted, see http://postgrey.schweikert.ch/help/example.com.html (Email / SMTP)450 4.7.1 Greylisted,…451 4.3.0 Local error in processing — SMTP: 451 4.3.0 Error: queue file write error / 451 Requested action aborted: local error in processing (Email / SMTP)451 4.3.0 Local error…452 4.5.3 Too many recipients — SMTP: 452 4.5.3 Your message has too many recipients / 452 Too many recipients received this hour (Email / SMTP)452 4.5.3 Too many re…534 5.7.9 Application-specific password required — SMTP: 534-5.7.9 Application-specific password required. Learn more at https://support.google.com/accounts/answer/185833 (Email / SMTP)534 5.7.9 Application…535 5.7.8 Username and Password not accepted — SMTP: 535-5.7.8 Username and Password not accepted. Learn more at https://support.google.com/mail/?p=BadCredentials (Email / SMTP)535 5.7.8 Username an…EMFILE — Too many open files (EMFILE) (Linux)EMFILEfork: retry: Resource temporarily unavailable — fork: retry: Resource temporarily unavailable (process/thread limit) (Linux)fork: retry: Resource…550 5.4.5…

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