What the bounce says
Exact wording as it appears in the rejection or NDR. Placeholders such as x.x.x.x and example.com stand for your own address and domain.
550-5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. For more information, go to https://support.google.com/mail/?p=NoSuchUser
Gmail could not find a mailbox for the address you sent to. The wording — "the email account that you tried to reach does not exist" — is literal: no Gmail or Workspace user, alias or group has that address.
Most common causes
- A typo in the local part or domain
- The account was deleted or never existed
- A Workspace user was removed
- An alias that was removed
What to verify next
- Double-check the address for typos and stray spaces
- Confirm with the recipient through another channel
- For Workspace domains, confirm the user or alias exists
- Remove the address from lists to protect reputation
Check the address, not the server
A typo, an extra space, a dot in the wrong place or an old address are the causes. Gmail addresses ignore dots and are case-insensitive, so those are not the issue; wrong letters and wrong domains are.
For Workspace domains, the address may have belonged to a user who was deleted, or to an alias that was removed.
- Verify the address independently.
- Dots and case do not matter for gmail.com.
- Workspace users and aliases can be removed.
Protect your reputation
Repeated sends to non-existent addresses are a spam signal. Remove the address from every list and CRM after a 5.1.1, and validate lists before large sends.
If it is your Workspace domain
Confirm the user or alias exists in the admin console and that the domain is verified and its MX points at Google.
Best diagnostic path
Mail Failure Doctor
Classify the complete rejection and preserve provider-specific diagnostic context.
Open analysis → Live analysisEmail Infrastructure Digital Twin
Map the domain’s public mail infrastructure and provider relationships before remediation.
Open analysis →Known limits
- Gmail does not say whether the address existed previously.
- Some Workspace catch-all configurations change the outcome.
Common questions
The person definitely has that Gmail.
Then the address as typed differs from theirs. Ask them to send you a message and reply to it.
Does Gmail retry?
No. 5.1.1 is permanent for that attempt.
Why does my list keep producing these?
Address decay. Validate before sending and suppress bounces immediately.
Why the exact message matters
The same status family can be triggered by different conditions, and providers frequently add diagnostic text that narrows the issue. Use the complete rejection text rather than treating the numeric code as a complete diagnosis.
Provider reference
For the provider-defined meaning and current requirements, review Gmail SMTP errors and codes.