"The email platform we needed didn't exist. So we built it."
Jesse Hanley, Founder at BentoTransient (4xx)
The mail server encountered a temporary failure. If the command is repeated without any change, it might be completed. Mail servers can use temporary failures like this to keep untrusted senders at bay.
1 responses for SMTP 452
smtp;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
This Gmail mailbox is over quota and cannot accept new mail. Retry later, or reach the person another way so they can free space.
1 responses for SMTP 452
smtp;452 temporary domain failure <example@example.com>
Yahoo reported a temporary domain failure. Retry with backoff. Investigate if the same domain keeps failing.
1 responses for SMTP 452
smtp;452 4.3.1 Insufficient system resources (TSTE) [outlook.com]
Outlook is out of system resources on the receiving side. Retry later. Their admins need to free capacity.
2 responses for SMTP 452
smtp;452 <example@zoho.com> Mailbox delivery restricted by policy error
Zoho blocked delivery under the recipient domain's policy. Contact that domain's admin to adjust filters if the mail is legitimate.
smtp;452 4.3.1 Temporary System Error
Zoho is not accepting mail for this domain right now. Retry with backoff.
2 responses for SMTP 452
smtp;452 4.1.1 <example@comcast.net> too many recent messages; Try again later
This Comcast mailbox received too many recent messages. Wait and retry at a lower rate.
smtp;452 4.1.1 <example@comcast.net> user over quota
This Comcast mailbox is over quota. Retry later, or ask the recipient to free space.
1 responses for SMTP 452
smtp;452 4.5.3 rate limit exceeded
Rambler rate-limited this recipient. Wait and retry. Slow sends to that mailbox if it continues.
Response catalog adapted from the MIT-licensed SMTP Field Manual by ActiveCampaign / Postmark.
