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How Email Bounces can Affect Deliverability

Email Bounces

Bounced emails are like all the supervillains in the world combined.

They reduce your income, make your email support provider bill bigger, and can even cause blacklisting of your entire list.

What is email bounce rate?

Bounce rate stands for the percentage of addresses in your list that did not receive your email because it was returned (bounced) by a recipient mail server.

Fortunately, though, things are getting better in terms of delivery for the average sender: an Epsilon study suggests that about 4 percent of email campaigns were bounced in the 3rd quarter of 2010 (mind that the email bounce rate relies heavily on the industry, though).

Why do emails bounce in the first place?

The most common reason for an email to bounce is a misspelled email address. Maybe the subscriber uses a local email provider, which doesn’t accept your email due to its size, or has a full inbox. A network failure can also make your email bounce in rare cases, or your sending address might have been blocked by the mail server. It’s also important to distinguish between hard and soft bounces.

What are the main differences between a soft and hard bounce?

Hard bounces are undelivered messages that are permanently kept from reaching the intended recipient. Examples include blocked email, and an email sent to mistyped and no longer existing email addresses.

Soft Bounces are email bounces from emails that were sent to an existing address but were sent back. This can happen due to a full inbox, your message being too large, or because of overwhelmed server capacity.

When comparing soft bounce with hard bounce blocks, one can see the former as a short term issue which doesn’t require the removal of certain emails off your list, and the later as a reason to remove specific email addresses from your list (invalid or non-existent addresses).

Bounces can affect your entire list. ISPs can blacklist you because spammers commonly employ a technique known as a “Direct Harvest Attack”, and the respective ISP can mistake you for a spammer if you send email to non-existent addresses, as is done during a “direct harvest attack”.

What is a high email bounce rate?

The average bounce rate is less than 2% and signalizes a healthy email campaign.

If the email bounce rate is above 2% it could suggest the start of a problem that can easily be solved with minor tweaks in your email’s content.

However, if your bounce rate has reached a level of 5%-10% you could be facing a larger problem that needs to be resolved.

Needless to say, you shouldn’t send emails after hard bounces, you should delete them right away, and after three soft bounces sending an email becomes a long shot.

7 things you can do to decrease the bounce rate

1. Clean the list you own regularly.
This is a no-brainer. Remove bounced email addresses regularly, and re-engage the customers when doing it can yield returns. Besides, clean email lists give more accurate statistics, and will greatly lower your email bounce rate. For more information on list maintenance, check out our article on email list hygiene.

2. Skim read the bounced addresses.
Chances are that some addresses need correction if you don’t follow a double-opt in system. Even if you do, though, you might want to correct the emails that were mistyped (.ocm, htomail, etc) for the user to get the chance to confirm his or her subscription.

3. Use double opt-in.
Double opt-in confirms each address upon subscribing, reducing the possibility of mistyped addresses to practically zero. In theory, by doing this and you won’t have to do #2.

4. Try a win-back campaign.
Re-engaging inactive subscribers is an option you should consider if your open rates are falling low. A win-back campaign will trim your list greatly, but the result will be a cleaner list with more possibilities to deliver.

5. Send useful and relevant emails.
By doing so you will not only keep your reputation in check but also potentially sell more, experience fewer complaints and have soaring email open rates. It is tempting to send short-term campaigns with no real value to the customer because they can work well. But don’t. Just don’t.

6. Make sure your letters aren’t “spammy”.
A letter can be filtered by the webmail client (Gmail, AOL, Yahoo) or desktop email software (Outlook, Thunderbird, etc.), so ensure that your email has no phrases like “Cialis, Viagra, sex tape”, and so on prior to sending it.

7. Remove spam traps and maintenance addresses.
Scan for addresses such as,, etc. Addresses like are most likely added by people who don’t very much like you or think they are funny. Do your best to remove them.

We would like to hear how you are dealing with bounced emails. Which of the 7 tactics did you use?

How Email Bounces can Affect Deliverability
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