Troubleshoot: Messages summary code meanings

Whitelisting Finalsite's Messages sending IP addresses in your school's email server ensures that bulk messages don't get blocked or filtered as spam before reaching recipients. This is particularly important for districts whose mail servers apply strict filtering to incoming bulk email.

Simple Mail Transfer Protocol (SMTP) is the communication protocol for sending email. Each time you make an SMTP call, it returns a response in the form of a three-digit code. This article will show you how to track errors by looking at the summary code in your Activity Log. 

In this article

• What is SMTP? 
• Where are codes found?  
• Common codes and summaries list

What is SMTP? 

This is an Internet standard communication protocol for sending and receiving email messages. There is a Summary code that is provided whenever a message doesn't reach its intended recipient. 

Where are codes found?  

• Navigate to Messages.
• Locate a Sent message that you would like to view the sending report for.
• Click on the View Reporting bar chart icon to the right of your Sent message. 
  
• This will open up Reporting. Click in the Raw Log tab. The Raw Log is available for 90 days after your message is sent. It contains full records of Delivered, Opened, Clicked, Complained, Bounced and Dropped data. Search for a particular email address to find out how the recipient engaged with this message, or you can filter the records by clicking on each status.
• You can filter this log with the Filter by Event dropdown based on the following recipient events: Bounced, Clicked, Complained, Delivered, Dropped, and Opened.

• The first digit of the code tells you what kind of response it is.
  • 200 responses are usually success responses
  • 400 responses are usually deferrals
  • 500 responses are hard failures that are not retried
• The most common code you’ll see is 250, which means the message was accepted by the recipient server and your send was successful.

Common codes and summaries list

• 421: Messages are temporarily deferred because of recipient server policy. Often, this is because too many messages or connections have been made in too short a time.
• 450: The message failed because the recipient’s mailbox was unavailable, perhaps because it was locked or was not routable at the time.
• 451: The message simply failed, usually due to a far-end server error.
• 452: The message has been deferred due to insufficient system storage.
• 501: Syntax error in parameters or arguments. This usually indicates an issue with the email address format.
• 502: Command not implemented. The server does not support the command issued.
• 503: Bad sequence of commands. The commands were sent in an incorrect order.
• 504: Command parameter not implemented. The server does not support one of the command parameters.
• 535: Authentication credentials invalid. The provided authentication credentials are incorrect.
• 550: The user’s mailbox was unavailable, usually because it could not be found, or because of incoming policy reasons. It is likely a fake, or it was mistyped.
• 551: The intended mailbox does not exist on this recipient server.
• 552: The recipient’s mailbox has exceeded its storage limits. This is usually a sign this is an abandoned email.
• 553: The message was refused because the mailbox name is either malformed or does not exist.
• 554: This is a default response that can be caused by a lot of issues. There is usually an accompanying message that will tell you more about the response.
• 602: The message cannot be delivered to the recipient after attempting to send for eight hours.
• 603: This code indicates that the recipient or their system intentionally rejected the call—unlike a busy signal or network error, this may result from a manual decline, a configured rule like Do Not Disturb, or a spam filter or call-blocking system.