Google offers both a freemail option (Gmail) and a range of online services for business domains (Google Workspace). They boast total automation and machine learning as their spam filtering and anti-abuse systems. There are few methods for contacting a human to review delivery issues, since options for human intervention in these kinds of processes are also limited. Instead all senders should be monitoring their domains at Google Postmaster Tools daily for insight into reputation and performance.
Domains
gmail.com · googlemail.com
Codes
421 · 450 · 451 · 452 · 550 · 552 · 553
- 421↑
421 4.7.0 [x.xx.xx.xx] Our system has detected that this message is suspicious due to the very low reputation of the sending domain. To best protect our users from spam, the message has been blocked. Please visit https://support.google.com/mail/answer/188131 for more information. - gsmtp
Gmail has determined that the sending domain has a low reputation, so messages are now temporarily rejected. See Google's documentation on how to determine the source of this poor reputation and how to improve deliverability.
421 4.7.0 [x.xx.xx.xx] Our system has detected that this message is suspicious due to the nature of the content and/or the links within. To best protect our users from spam, the message has been blocked. Please visit https://support.google.com/mail/answer/188131 for more information. - gsmtp
Gmail has determined that the content of the message has a low reputation. See Google's documentation on how to determine the source of this poor reputation and how to improve deliverability.
421 4.7.28 [x.xx.xx.xx] Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been temporarily rate limited. Please visit https://support.google.com/mail/?p=UnsolicitedRateLimitError to review our Bulk Email Senders Guidelines. - gsmtp
Gmail has determined your messages are unsolicted, so messages sent over this IP may be temporarily rejected. See Google's documentation for best practices on sending to Gmail to avoid this.
4.7.32 This mail has been rate limited because there is no DMARC alignment
The message is missing DKIM or SPF alignment for DMARC. Make sure your messages are passing DMARC. This message started appearing on January 21st, 2024 ahead of Gmail's new 2024 sender requirements.
- 450↑
450 4.2.1 The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, please visit https://support.google.com/mail/?p=ReceivingRate - gsmtp
The email address is currently receiving an email at a high rate. Sending email in the future will most likely be successful.
- 452↑
452 4.2.2 The email account that you tried to reach is over quota. Please direct the recipient to https://support.google.com/mail/?p=OverQuotaTemp - gsmtp
Google Mail has has restrictions on the amount of storage a user can use, the recepiepnt is over their storage limit and unable to receive new messages. They will need to delete emails to start to receive messages again. Once they've done this, they'll be able to start to receive messages again.
- 550↑
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. Learn more at https://support.google.com/mail/?p=NoSuchUser - gsmtp
550 5.2.1 The email account that you tried to reach is disabled. Learn more at https://support.google.com/mail/?p=DisabledUser - gsmtp
550 5.2.1 The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. For more information, please visit https://support.google.com/mail/?p=ReceivingRatePerm - gsmtp
While this could indicate a busy or inactive Gmail user, sometimes this indicates the recipient is being 'mail bombed' - a tactic used to disable a victim's mailbox in order to hide malicious activity. Please verify the recipient was not added to your list by an automated script or other malicious entity.
550 5.7.1 [x.xx.xx.xx] Our system has detected that this message is likely suspicious due to the very low reputation of the sending domain. To best protect our users from spam, the message has been blocked. Please visit https://support.google.com/mail/answer/188131 for more information. - gsmtp
Gmail has determined that the sending domain has a low reputation, so messages are now permanently rejected. See Google's documentation on how to determine the source of this poor reputation and how to improve deliverability.
550 5.7.1 [x.xx.xx.xx] Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. Please visit https://support.google.com/mail/?p=UnsolicitedMessageError for more information. - gsmtp
Gmail has determined your messages are unsolicited, so messages are now permanently rejected. See Google's documentation for best practices to monitor and investigate this.
550 5.7.1 Unauthenticated email from example.com is not accepted due to domain's DMARC policy. Please contact the administrator of example.com domain if this was a legitimate mail. Please visit https://support.google.com/mail/answer/2451690 to learn about the DMARC initiative. - gsmtp
The sent message failed the DMARC policy for the sending domain. If the sending domain has a reject policy set for DMARC, the message must pass DKIM or have SPF aligned to the domain with a custom Return-Path. To resolve this, you'll need to contact your email service provider to see how to send a message that passes DMARC support.
550 5.7.1 [x.xx.xx.xx 14] Messages missing a valid address in From: header, or having no From: header, are not accepted. - gsmtp
In most cases this is the result of a malformatted From name or email address.
- 552↑
552 5.2.2 The email account that you tried to reach is over quota. Please direct the recipient to https://support.google.com/mail/?p=OverQuotaPerm - gsmtp
552-5.2.3 Your message exceeded Google's message size limits. Please visit http://mail.google.com/support/bin/answer.py?answer=8770 to review our size guidelines.
552-5.7.0 Our system detected an illegal attachment on your message. Please visit http://mail.google.com/support/bin/answer.py?answer=6590 to review our attachment guidelines.