Deciphering Those Bounce Error Codes

If you've been conducting some campaigns recently, you might've notice the new swanky  (but rather daunting) bounce reports being generated from BlinkCampaign.

Here's a quick low-down on what those error codes really mean:

500

The recipient's email server is not recognizing the email that was sent out or was not formatted in the way the server expected. This could occur for longer emails.

501

This is due to syntax errors in the email address, outside of those that are automatically cleansed by BlinkCampaign. Some of your client's email servers may not recognize, and do not have addresses with underscores for example. This is also indicative of an invalid email address.

502

The mail was not delivered because it is not supported by a particular server. This may the case for email campaigns with a HTML only version (no plain text version) and the recipient's email server can only receive plain text format.

503

This usually indicates a problem with the network and communication to the recipient's email server.

504

A particular valid command was not implemented on the recipient's email server, and thus, cannot deliver the mail. This is a rare issue.

550

This is probably the most common bounce error you'll receive for your email campaigns. Basically it means the mail was not delivered due any number (but not limited to) the following reasons in plain English:

• The account doesn't exist (The recipient might have closed the account or left an organization
• The recipient's email server requires authentication (which has to be manually setup and varies from server to server
• Certain ISPs require you to have the same From address as the domain where the mail is being sent from
• The recipient's server is down and has given up retrying x number of times

552

In a nutshell, your recipient's mailbox is full and needs some spring cleaning before your email campaigns can get through.

553

This error code means the email address is invalid. The difference from a suspended or closed account is that this email account never existed in the first place.

554

Yet another sort of invalid email address or does not exist anymore. This error is quite typically specified and returned from Yahoo:

554 delivery error: This user doesn't have a Yahoo.com account

554 delivery error: Sorry your message to [email address] cannot be delivered. This account has been disabled or discontinued.

Other less common bounce errors you may encounter

421 - the email server or ISP is unavailable. This may be caused by many things such as the server administrator stopping the mail service, or rebooting the mail server.

450 - The email server could not access the recipient's mailbox. This could be caused by a process on the recipient's email server tidying up the mailbox (think archiving in Outlook), the mailbox could be corrupt, or the remote mailbox may be stored on another server which is currently offline. It may also be caused by the remote mail server not wanting to accept the mail (user may have blocked the domain, blacklisting, etc).

451 - The email has bee aborted by the recipient's server due to overload. This is due to high traffic at certain times and prevents the successful delivery of the message.

452 - Insufficient disk space on the recipient's email server. This can occur when an ISP's mail server goes down, and when it comes back up, there is a huge spike in traffic as mails may have been queued for delivery or frequent attempts to re-try mails for the ISPs email account users due to the downtime.

We hope this analysis of bounces helps you understand your subscriber lists better. Analyzing your bounce mails is a great way to further profile your subscriber list and also help you determine which time and day would be the best delivery day for your email campaigns.