SMTP 550 5.4.5
daily sending limit exceeded (Gmail)
SMTP 550 5.4.5 is Google's "daily user sending limit exceeded". Your Gmail or Google Workspace account has sent more messages or recipients than Google allows in a rolling day, and it will refuse further sends until the limit resets. It is about your account, not the recipient.
Should you remove the address?
Keep the address; fix the sending side
Keep every address. Nothing is wrong with the recipients; Google stopped your account from sending more today.
Block. Retrying changes nothing until the cause on your side is fixed.
How it appears
550 5.4.5 Daily user sending limit exceeded.
550 5.4.5 Daily SMTP relay limit exceeded for user.
What causes it
- A campaign or mail merge was sent from an ordinary Gmail or Workspace mailbox.
- An app or script sending through your account sent more than expected.
- The SMTP relay service hit its own daily limit for the user.
How to fix it
In order — try the first one first.
- Wait for the limit to reset. Google's limits work on a rolling 24-hour window.
- Move bulk and cold sending to a dedicated sending service built for volume.
- Check the account for apps or scripts you did not expect to be sending.
- Do not remove the recipients. They were never contacted.
Who sends it
Gmail and Google Workspace, for both regular sending and the SMTP relay service, which has its own daily limit.
Gmail
Reply text Daily user sending limit exceeded.
The SMTP relay version reads "Daily SMTP relay limit exceeded for user."
Common questions
- What does SMTP 550 5.4.5 mean?
- SMTP 550 5.4.5 is Google's "daily user sending limit exceeded". Your Gmail or Google Workspace account has sent more messages or recipients than Google allows in a rolling day, and it will refuse further sends until the limit resets. It is about your account, not the recipient.
- Should I retry a 550 5.4.5 error?
- No. 550 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.
- How do I fix SMTP 550 5.4.5?
- Wait for the limit to reset. Google's limits work on a rolling 24-hour window.
- Is 550 5.4.5 a hard bounce or a soft bounce?
- 550 5.4.5 is a block rather than a classic hard or soft bounce. The rejection is about your sending (authentication, reputation, content or the recipient's policy), not about whether the address exists. Retrying changes nothing until the cause on your side is fixed.
- Should I remove the address after a 550 5.4.5 bounce?
- Keep every address. Nothing is wrong with the recipients; Google stopped your account from sending more today.
- Will verifying my list prevent 550 5.4.5?
- Indirectly. Every hard bounce still uses part of your daily allowance, so removing dead addresses first means more of the limit goes to real people.
Clean the list before the next send.
A bounce report only tells you about the addresses you already mailed. The rest of the list has the same kinds of dead mailboxes in it, and each one becomes a hard bounce recorded against your domain the moment you send.
- A real SMTP mailbox check on every row, before anything is sent
- Dead and mistyped addresses split out, so they never reach your sending tool
- Catch-all, disposable and role addresses flagged alongside
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.
Other 550 replies
- 550 5.1.1 — mailbox does not exist
- 550 5.7.1 — message refused by policy
- 550 5.4.1 — recipient address rejected, access denied
- 550 5.2.1 — mailbox disabled, not accepting messages
- 550 — mailbox unavailable
- 550 5.1.0 — address rejected, other address status
- 550 5.1.10 — recipient not found (Microsoft 365)
- 550 5.1.8 — bad outbound sender (Microsoft 365)
- 550 4.4.7 — message expired in the queue
- 550 5.7.25 — no PTR record for sending IP (Gmail)
- 550 5.7.26 — blocked, sender unauthenticated (Gmail)
- 550 5.7.27 — SPF authentication failed (Gmail)
- 550 5.7.28 — unusual rate of unsolicited mail (Gmail)
- 550 5.7.23 — SPF violation (Microsoft 365)
- 550 5.7.124 — sender not in allowed senders list (Microsoft 365)
- 550 5.7.509 — DMARC failed, policy reject (Microsoft 365)
- 550 5.7.606-649 — banned sending IP (Microsoft)
- 550 5.7.705 — tenant has exceeded threshold (Microsoft 365)
- 550 5.7.708 — traffic not accepted from this IP (Microsoft 365)
- 550 5.7.750 — blocked from sending from unregistered domains (Microsoft 365)
- 550 5.7.515 — authentication required for high-volume senders (Outlook.com)
- 550 5.7.1 S3140 — IP range on Outlook.com block list
- 550 5.5.0 — Mailbox unavailable (Outlook.com, Hotmail)
- 550 5.7.12 — Sender not authenticated by organization (Microsoft 365)
- 550 5.7.513 — Blocked by the recipient's own block list (Microsoft 365)
Sources
- Source: Google Workspace Admin Help: Gmail SMTP errors and codes
- Source: RFC 3463: Enhanced Mail System Status Codes
Provider wording is quoted only where the provider publishes it.
Last reviewed 2026-10-22