As a B2B company, you will often send emails to customers. However, do you also look at the data report of a sent e-mail? After all, there may be a number of emails that were not delivered. In other words, the bounce rate is quite high. You just have no idea why.
Many of our clients run into this problem. That's why we took a deeper look into where those email bounces are coming from.
Why is your email being bounced?
Often this has a very simple reason: the e-mail address is incorrect. For example due to a typing error or the e-mail address no longer exists. You can recognize an e-mail bounce by notifications with subjects like: Non-Delivery Report/Receipt, Delivery Status Notification or Non-Delivery Notification..
The difference between soft bounces and hard bounces
An e-mail bounce is divided into two categories: a soft bounce and a hard bounce.
A soft bounce means that the email did not arrive because of a full mailbox, a temporary network problem at the mail server or when the email/file is too large. So this is usually only temporary.
A hard bounce is permanent, so for example, if the e-mail address is incorrect. Or when the sending mail server is blacklisted. The mail will then never arrive at the e-mail address in question.
Delve into bounce codes
When an e-mail bounces, it always carries a (status) code. This code consists of three digits and a subject, for example: '550 No such recipient here'. The code can also be extended with an additional code, for example: '550 5.1.1 The email account that you tried to reach does not exist'..
These codes are listed under RFC 3463. When you enter this code into this RFC, you will quickly find out why an e-mail does not arrive at the address.
This is an example of a bounce code message: '550 5.1.1 The email account that you tried to reach does not exist'
The response from the remote server was:
550 5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. Learn more at https://support.google.com/mail/?p=NoSuchUser p52si23555697wrc.192 - gsmtp
Final-Recipient: rfc822; dave-bestaat-niet@digiter.nl
Action: failed
Status: 5.1.1
Remote-MTA: dns; aspmx.l.google.com. (2a00:1450:400c:c06::1a, the server for
the domain digiter.co.uk.)
Diagnostic-Code: smtp; 550-5.1.1 The email account that you tried to reach does not exist. Please try
550-5.1.1 double-checking the recipient's email address for typos or
550-5.1.1 unnecessary spaces. Learn more at
550 5.1.1 https://support.google.com/mail/?p=NoSuchUser p52si23555697wrc.192 - gsmtp
Last-Attempt-Date: Mon, 13 Mar 2017 01:05:50 -0700 (PDT)
The subject of the bounce message actually says it right away. Then when you look up the code in the RFC, you get this explanation:
5.XXX.XXX Permanent Failure
A permanent failure is one which is not likely to be resolved by resending the message in its current form. Some change to the message or the destination must be made for successful delivery.
The additional code then provides another detailed explanation of this:
X.1.1 Bad destination mailbox address
The mailbox specified in the address does not exist. For Internet mail names, this means the address portion to the left of the "@" sign is invalid. This code is only useful for permanent failures.
So this is a hard bounce. You will have to approach the contact in a different way.
What is email spoofing?
You may also receive an e-mail bounce from a message you didn't send at all. This is called e-mail spoofing. Spoofing is mainly used by spammers, who send an e-mail from a fake sender (your e-mail address) to an e-mail address that does not exist. The goal is for you to click on the links or attachments in the email. In this way, you are directed to phishing sites or a malware is installed on your computer.
You recognize a spoof e-mail by diving into the e-mail's source code. You then do a check on the so-called Received-SPF (Sender Permitted Form). However, this is very technical.
Something simpler you can do is:
- Setting your spam filters to a higher / stricter level;
- Your mail provider offers services for the mail server to recognize the important people around you. You can do this, for example, with Gmail Priority Inbox or Apple VIP;
- Never open suspicious attachments or unfamiliar links in emails
