iCloud: Email is delayed or returns to sender with 452 alert message

Delivery of an email message to your inbox is delayed or returned to the sender with a "452" alert.

The sender may see the following statement in the returned message:

"SMTP error from remote mail server after initial connection: host smtp-mx5.mac.com (for mac.com recipient addresses) or smtp-mx5.me.com (for me.com recipient addresses) [IP address]: 452 try later."

This can happen if a certain percentage of messages originating from the sender's IP address have been identified as "spam" (unsolicited bulk email). For example, if a sender sends numerous emails, they may exceed the ISP's sending limits and be flagged as spam. In order to reduce the amount of "spam" that reaches an @me.com or @mac.com Inbox, the mail servers may place restrictions on messages delivered from certain IP addresses. This can result in delayed or returned mail with a 452 message.

Steps the sender can take

When trying to diagnose the issue, the sender should note the following:   

  1. The exact @me.com or @mac.com address the message was sent to.   
  2. The date and time the message was sent.   
  3. The reason included with the alert number, such as "452 try later".   
  4. The contents of the returned message.

If the sender continues to receive returned messages, try the following:   

  1. Contact the recipient by phone or other means and make sure the issue is known.   
  2. Try sending the message again from a different location (use icloud.com/mail from a different computer, for example).
  3. Send mail from a different IP address, or different ISP.

If the sender is unable to reach the intended recipient, he or she can contact iCloud Support for further assistance. It is recommended that the sender have the full headers and body of the returned message available to provide to support.

Steps you (the recipient) can take

Suggest the above steps to the sender if you are aware of the issue.

If that does not help, you can contact iCloud Support for further assistance. Before contacting support, it is recommended that you obtain the full headers from an email sent from the affected sender. If you were able to receive email from the sender previously, you can provide those headers to support. Alternatively, if you have an alternate email address, you might consider requesting the sender to send a test message to that address. If that is not possible, provide the full headers and body of the returned message to support.

Obtaining headers

To gather the full headers from an email message, follow the steps in this article. If you are using an email application not described in that article, please refer to your application's help for more information on obtaining headers.

Learn more

For more information, see iCloud: Troubleshooting iCloud Mail.

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