Is 550 5.4.5 a hard bounce or a soft bounce?

550 5.4.5 is a permanent failure (a hard bounce): the receiving server won't accept this message if you send it again unchanged. But the cause is not the recipient's address, so treat it differently from a 'user unknown' bounce.

How many emails can I send per day from Google Workspace?

Google's published limit is 2,000 messages per day per user (500 on a trial account), with additional limits on total and external recipients. For cold email, stay far below that: a few dozen sends per inbox per day protects both the account and your domain's reputation.

550 5.4.5 Gmail Error: Meaning and Fix

Q: Should I remove the contact after a 550 5.4.5 bounce?

No. Don't suppress the recipients; nothing was delivered. Pause the inbox, then resend after the limit resets, at a lower daily volume.

What 550 5.4.5 means

This bounce comes from your own provider, not the recipient's. Google returns 550 5.4.5 'Daily user sending limit exceeded' when a Gmail or Google Workspace account sends more than it's allowed in a rolling 24-hour period. The message wasn't sent to anyone.

Google's published limit for Workspace accounts is 2,000 messages per day (500 for trial accounts), with separate caps such as 3,000 external recipients per day. After hitting a limit, Google says users can't send new messages for up to 24 hours; they can still receive mail.

What the bounce looks like

The wording providers document for this code. Your bounce may add an IP address, a session ID or a help link after it.

Gmail

550 5.4.5 Daily user sending limit exceeded.

Gmail

550 5.4.5 Daily SMTP relay limit exceeded for user.

Why cold emailers see 550 5.4.5

Sending too many cold emails from one inbox. Cold email should run far below Google's limits; most teams keep each inbox to a few dozen sends a day.
A sequence that fires follow-ups for a large list on the same day as new first-touch emails.
A Workspace trial account, which has a much lower limit.
Google SMTP relay variant: 'Daily SMTP relay limit exceeded for user'.

How to fix 550 5.4.5

Stop sending from that inbox until the limit resets. Retrying sooner only adds failures.
Lower the daily cap per inbox in your sending tool and spread volume across more inboxes and domains.
If the account is on a trial, upgrade before using it for outreach.
Resend the failed messages after the reset. The recipients were never contacted.

Retry or suppress?

Don't suppress the recipients; nothing was delivered. Pause the inbox, then resend after the limit resets, at a lower daily volume.

Reading the code

The basic code 550 means "Mailbox unavailable or message refused (permanent)" under RFC 5321. In 5.4.5, the 5 is the class (permanent failure) and the 4 is the subject (network and routing). The detail number 5 is registered in RFC 3463 / the IANA registry as "Mail system congestion".

Class 5: Permanent failure; Resending the same message won't work. Something about the message, the recipient or the sender has to change first.
Subject 4: Network and routing; A problem with networking, DNS or routing between servers.
Detail 5.4.5: Mail system congestion

Check the rest of your setup

Paste the headers of a message that did get through into the email header analyzer to confirm SPF, DKIM and DMARC pass, and check your domain with the SPF, DKIM & DMARC checker. The deliverability checklist covers the rest of a healthy sending setup.

Got a different bounce? Paste it into the SMTP error code lookup to decode it.

550 5.4.5: Daily sending limit exceeded (Gmail)