Bounce Rates and Spam Complaints

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What Are Bounce Rates?

You may already be familiar with the concept of deliverability rate. Bounce rates reflect the opposite: while deliverability rates compares the number of the emails that reached an inbox with the number of emails sent, bounce rates compare the number of sent emails and the ones that did not reach a recipient. By definition, then, an email's bounce rate reflects the number of emails rejected by the receiving server.

All Email Reports contain information about the delivery details of your email sending. To see which Profiles bounced and their corresponding bounce code and reason, export the Bounces section of the Email Report. Read more about Email Reports....

Email bounces can be divided into three categories:

Hard Bounce

These are the ones to look out for. It means that it was impossible to deliver the email. Once a hard bounce happens, we won't make more attempts to deliver to that profile in the Email tool activity where the bounce happened.

However, if a hard bounce happens three (3) times for the same profile, APSIS One will stop sending emails to the profile altogether. Note that SMS bounces are treated the same in APSIS One.

These are all the hard bounce reasons:




Hard - Unknown


Hard - General hard bounce


Hard - Recipient email does not exist


Hard - Domain name does not exist


Hard - Closed email account

Soft Bounce

Soft bounces indicate a temporary issue, and are therefore handled differently by APSIS One.

If a soft bounce happens, APSIS One continues to try to deliver the email every hour for up to 48 hours. If the email is still not delivered, the profile is not affected and will still be included in future sendings.

These are all the soft bounce reasons:




Soft - Mailbox is full


Soft - Recipient email server is currently too busy


Soft - Email account is inactive


Soft - General error


Other - Unknown

Technical Bounce

A technical bounce is considered a type of soft bounce. Technical bounces occur when the email server rejects the email due to technical errors.

APSIS One responds to technical bounces just the same as with soft bounces: APSIS One continues to try to deliver the email every hour for up to 48 hours. If the email is still not delivered, the profile is not affected and will still be included in future sendings.

However, if you have a large amount of technical bounces, we recommend that you contact support.

These are all the technical bounce reasons:




Technical - General error


Technical - Network error


Technical - SPF authentication error


Technical - DMARC authentication error


Technical - DKIM authentication error

Before and After Bounces

Monitoring bounce rates and spam complaints is an important part of sending emails to APSIS One Profiles. You can easily do this with the Email Report once your email activity has been sent, by checking periodically during the course of 2 or 3 days.

Of course, preventing bounces is just as important as taking measures after noticing a high bounce rate.


Preventing Bounces

There is no one-size-fits-all method of preventing bounces, so it's important that you make time to periodically check your bounce rates and take preventive action.

It's something that you will be doing every now and then, perhaps once a month. Not only would you be preventing bounces, but also keeping your Consent lists and Topics clean from clutter, as well as gaining significant insights about your APSIS One Audience.

There are list cleaning services that offer to do some of these things for you. However, these services are usually costly and will not guarantee that your Audience will be rid of spam traps. Quite the contrary, with APSIS One it is much simpler to do these things yourself in a smart, intuitive platform with the features you need.

Don't forget that both the Email and SMS tool identify Profiles that hard bounce in your activities, and after 3 hard bounces they're excluded from your sendings. Read more about hard bounces above.

Here's what you can do to help prevent bounces.

From Consent Management:

  • Clean up inactive profiles.

Identify inactive profiles and unsubscribe or delete them. You can also create segments for these profiles and exclude them from receiving your emails. Profiles that match a segment can also be exported in order to unsubscribe or delete them via the File Import Wizard.

  • Re-engage your inactive profiles.

You can do different things to re-engage a profile. For example, you can create a Marketing Automation flow to re-engage your inactive profiles. If they don't respond positively, you can confidently exclude or remove them from your Audience.

  • Ask your profiles to whitelist you.

You may include a message in your Welcome emails, especially to address the cases in which the email may wrongfully land in the spam folder.

  • Keep track of bounces and spam complaints.

And do not send to profiles who bounced, unsubscribed or reported your emails as spam.

  • Use the File Import Wizard sensibly.

Make sure that all addresses are real and provided with consent.

Do not re-subscribe profiles that have unsubscribed unless you've received explicit, informed consent.

Do not import files with email addresses or any contact information that was provided by a third party.

Under any circumstance, do not harvest email addresses from websites, buy or rent email lists. It is very difficult if not impossible for you to prove that the individuals provided their consent to email communications, and even more so specifically to your brand's communications. Also, it goes against APSIS' terms of service since it will result in serious consequences including APSIS' servers being blacklisted and hurting its sender reputation (whether a sender can be trusted or not).

High Bounce Rates

Keeping an eye on Email Reports for bounce rates and spam complaints is an essential part of email marketing activities and working with the APSIS One Email tool. Naturally, you may need to take action depending on what your bounce rates are for each Email activity.

A bounce rate of less than 5% is considered normal, and as long as you're actively and periodically taking steps in order to prevent bounces, there is no need to worry.

However, if your bounce rates are...

5% or Higher

10% or Higher

A bounce rate of 5% and up is a concern, so we recommend that you take a look at the Email Reports of the last few emails you've sent.

Then, take a look at the tasks described above on how to prevent bounces.

If you notice a lot of hard or technical bounces, we suggest that you contact Support directly

A bounce rate of 10% and up is considered a bad sending, meaning that there could be something wrong with the email addresses you've sent to, or perhaps an problem with your Email Authentication setup.

If you see a bounce rate of 10% or more, it's best that you contact Support for us to help you as soon as possible.

About Spam Complaints

Spam complaints reflect the number of Profiles who reported an email as spam through a feedback loop. Spam or spamming refers to the result or action of sending bulk email messages for marketing or advertising purposes without the recipients' request or consent.


In your Email Reports, the spam complaints reflect only the number of Profiles who reported, but not the number of emails that landed in a spam or junk folder. The reason that emails sometimes arrive to a spam or junk folder is usually previous spam complaints, technical reasons and the reputation of the sender. Your sender reputation can be greatly affected by consistently sending to spam traps.

Spam traps can be tricky to deal with, but sending to them greatly increases your chances of getting emails stuck in a spam or junk folder. As quoted above:

These are email addresses created to identify spam. Since they don't belong to a real individual, sending to a spam trap email address reflects that you obtained the address without consent. There are three types of spam traps:

  • Pure spam traps, which are created artificially to lure spammers and have never been associated to a real individual.

  • Recycled email addresses, which are emails that once belonged to an individual but they have been abandoned for so long that the email provider has repurposed it as a spam trap. If you happen to send to a recycled spam trap, it shows that you have failed to keep your profiles up to date and haven't cleaned up inactive profiles.

  • Invalid email addresses, which may be invalid either due to a typo or that an individual purposely provided a fake email address.

As a sender, the most important thing for you when it comes to spam is that you continue with your efforts the same way that you've been preventing bounces. As long as you maintain a steady sending schedule/frequency and a good Consent list hygiene, spam complaints should stay low.

However, you may want to make sure that your Email Authentication is all set and that all APSIS One Users in your account are aligned with your deliverability efforts.


A blacklist in email deliverability refers to a list of servers or domains that have been identified as spammers. The qualifying factor is usually sending bulk emails to to spam traps. There are different types of blacklists, some of them more severe than others.

This is how blacklisting affects email messages:

  1. Recipient servers have policies on whether they'll accept, flag or reject email messages from senders listed in a blacklist.

  2. The blacklist has no control over what action is taken, it merely provides the recipient server with the information about the sender. Recipient servers will "ask" the blacklist whether the sender is or isn't listed. If it isn't, the email reaches the recipient.

  3. In the case that the sender is in the blacklist, the recipient flags the email (causing it to land in the spam or junk folder), or rejects it altogether. This depends on the recipient's policies and at times they may even allow the blacklisted sender's email to go through without a problem.

  4. Some blacklists will list spamming sender domains for a long period of time, while others will only keep them for 4 or 5 hours. This depends on each particular blacklist, and recipient servers will often decide which blacklists they'll refer to in order to safeguard their users.

So, the key takeaway is that all of your deliverability efforts count when it comes to blacklisting. As long as you're taking care of your APSIS One Profiles, and avoiding spam traps, there should be no surprises.

However, if for any reason your emails were to be rejected due to a blacklist, know that our Deliverability professionals are constantly on the lookout for these events and will take action in order to identify what has happened, why the server was listed and what actions should be taken. For any blacklisting concerns, don't hesitate to contact Support.

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