Understanding Bounces in an Email Marketing Campaign?

Published by: Erica Sanford    |   Category: Blog, Email Marketing, Email Validation, IP Reputation    


A large percentage of your emails bounced, now what? Why did all of those emails bounce?

You have seen this scenario before. Those three little words that make you question your whole email campaign. “Your email bounced”. What does this mean? What kind of bounce is it? Can anything be done to reduce bounces and increase deliverability?

First, what is a bounce? A bounced email is one that never arrives in the recipient’s inbox or junk folder and is sent back, or bounced back, to the sender with an error message that indicates to the sender that the e-mail was never successfully delivered and why.

When an email bounces back, the server that bounced or rejected it will usually include a message telling you why a message bounced. This is the “SMTP reply”. This message will help you determine what kind of bounce caused your email not to be delivered and why. Below is the list of common bounce types.

Bounce Type



Hard Bounce


Soft Bounce – General


Soft Bounce – Dns Failure


Soft Bounce – Mailbox Full


Soft Bounce – Message Size Too Large


General Bounce


Mail Block – General


Mail Block – Known Spammer


Mail Block – Spam Detected


Mail Block – Attachment Detected


Mail Block – Relay Denied


Auto Reply


Transient Bounce


Subscribe Request


Unsubscribe Request




Bounce – But No Email Address Returned (Rare)


Non Bounce


While there are many types of bounces, the two main categories are Hard Bounces and Soft Bounces.

Hard Bounce -A hard bounce is an email message that’s returned to the original sender and is permanently undeliverable. The most common reason for hard bounce is an email addresses that does not exist, or a domain that does not exist.

Soft Bounce -This is when an email message has been sent and the recipient’s email box is either full, the server is down or flooded with messages.  An email can also be rejected based on content, IP Reputation, the message is too big, or a half dozen other reasons. Soft bounces are normally temporary.

So, now you understand the basics of hard and soft bounces. What you are probably asking yourself  is how can I reduce the number of bounces I am seeing? The first and most important step is to make sure your list has been recently cleaned and validated. This will enable you to get rid of dead emails you are trying to send to. “Don’t be fooled that Email List Cleaning and Validation equals 100% deliverability”.  This is a great article to read  that discusses deliverability and the benefits of scrubbing and validating your email list.

Email Answers offers email list cleaning and validation services which not only removes hard bounces, but removes complainers, spam domains, and BOT email addresses as well. This will help to improve your IP Reputation and increase your email delivery and stop a large percentage of rejections, improve inbox delivery and decrease soft bounces.

Soft bounces are not removed during a list cleaning and validation process due to the fact they are temporary in nature. Would you want to lose one of your long-time customers in an email list cleaning because their mailbox was full? I think not. This is why many times soft bounces are OK to get. Do not fret! The best advice on how to deal with soft bounces is to monitor them. If you have a soft bounce on the same email address from your last three campaigns, maybe it is time to figure out why it is bouncing and deal with it accordingly, instead of just removing it.


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