Understanding Undeliverable and Returned Emails

Do you get undeliverable email returns or bounce-backs? Do you wonder what they would mean? You are not alone. Here is the information you need to determine why specific emails are undeliverable and are being returned.

Happy to help! Emails get returned for various reasons. When you know what to look for, it is easy to find out why and what, if anything, you need to do about it.

Reasons Why Emails are Undeliverable

The several common reasons you may receive undeliverable email returns:

1. You had a typo in the email address, making it incorrect and therefore undeliverable. Conducive to dialing the wrong phone number.
   
2. The person you are emailing may have given you an incorrect email address, or you may have made a typo – that happens a lot. That’s why it’s not a bad idea to have your website’s contact forms require visitors to enter their email address twice.
   
3. The recipient’s inbox is full due to large attachments, incorrect server settings, or not logging in for an extended period. What often causes this problem is that the user has “leave mail on server” checked in their email program. This setting prevents downloaded emails from being cleared. All email is “left on the server”. Until that option is unchecked, all email is downloaded; this will continue to happen. (Leave this option unchecked unless you can micro-manage it.)
   
4. Your autoresponder message could not “auto respond” to a bogus email address that a spammer used to email you.
   
5. Your email was “spammy” and set off spam or network security filters.
   
6. Someone who has your email address on their system has a virus that is sending emails to non-existent email addresses and putting your address in the ‘From:’ field. This causes undeliverable virus-generated emails to be returned to you.

Deciphering Returns

There is a protocol to let you know when messages do not (for many different reasons) make it to the intended recipient. Therefore, you want to become familiar with how these messages precisely display the problem.

When an email bounces, the reason why is noted at the very top of the message. If you examine the returned message closely, you will see the problem. It will look similar to this:

The original message was received at Wed, 06 Oct 2021 10:38:48 -0700 (PDT)
from adsl-157-24-41.XXXXX.XXXXXX.net [12.345.67.89 ]

—– The following addresses had permanent fatal errors —–

(reason: 550 5.1.1 … User unknown)

—– Transcript of session follows —–
… while talking to www.businessemailetiquette.com.:
DATA
550 5.1.1 … User unknown

The above reflects that there is no such email address on the system (www.businessemailetiquette.com) – 550 user unknown.

You will see that the actual email message that the error refers to is displayed below the error message. There, you can determine whether it was an email you sent or if it was your autoresponder. In addition, you can decide if it was a virus-generated email that you did not send.

Email Error Codes

Here is a listing of the most common error codes you will see in undeliverable emails and what they mean:

Knowing Why Emails Bounce

These messages will vary depending on the systems involved in delivering the email. However, it is worth becoming familiar with these basics (or bookmarking this page [Ctrl +D]) so that you don’t panic and can take action to address what you can.