What is meant by bounce email?

The term "bounce email" refers to an email that has failed to reach the recipient's inbox and is therefore returned to the sender with an error message. This "bounce" can occur for various reasons, which are generally divided into two main categories: hard bounce and soft bounce.

  • Hard Bounce: This type of bounce occurs when the email is rejected permanently, such as because the recipient's email address is nonexistent, wrong, or disabled. This is a serious problem because it indicates that the email may never be delivered to that address.

  • Soft Bounce: This type of bounce is temporary and can be caused by various factors, such as a full inbox or a temporary problem with the recipient's server. In these cases, the email may be delivered with subsequent attempts.

Why are nonexistent emails (hard bounces) a problem in newsletters?

If you have many nonexistent or incorrect emails in your newsletter contact list, this can become a problem for several reasons:

  1. Sender Reputation: Email service providers (ESPs) monitor the bounce rate of your emails. If your newsletter has a high hard bounce rate, your reputation as a sender will suffer. A bad reputation can lead providers to filter your emails, sending them straight to the spam folder or blocking them altogether.

  2. Campaign Efficiency: Sending emails to non-existing addresses reduces the effectiveness of your campaign. You are paying to send emails that will never be read, and this can be a waste of resources.

  3. Possible Blacklists: A high bounce rate could result in your IP address being blacklisted. This prevents your emails from reaching not only the wrong addresses, but also valid ones.

Remember that if you send a lot of emails to free and popular email accounts such as libero.it, aruba.it, gmail.com a high number of hard bounces to one of these ISPs can be interpreted as spamming, as if we try to send unsolicited emails to users whose consent we never got and whose email we don't really have and try to guess. Our newsletter may also lose reputation if many users of these ISPs flag our email as unsolicited.

How to limit the problem of non-existent emails?

To reduce the problem of nonexistent emails and improve the effectiveness of your newsletters, you can adopt several strategies:

  1. Email Address Verification: Use email address verification tools before sending your newsletter. These tools can identify invalid email addresses, preventing you from adding them to your list. For example: zerobounce.net

  2. Double Opt-In: Implement a double opt-in process for your newsletter. This will require users to confirm their subscription via a link sent to their inbox, reducing the chance of email address errors.

  3. Periodic List Cleanup: Regularly remove addresses that generate hard bounces from your list. This will help you keep your list current and preserve your reputation as a sender. This operation is also recommended by the privacy guarantor, according to the principle of"data minimization" and should be done annually; it is patently useless to send emails to those who have shown no interest for several months or even years. Very useful for this purpose is our GDPR Data Minimizer module

  4. Campaign Monitoring: Analyze your campaign reports to quickly identify any problems with bounces and act accordingly.

Conclusions

When we send massive emails it is important to keep in mind that the maintenance of the contact list is very important, it is not strictly a GDPR-related factor, but also a technical one, too many bounce emails, but also too many uninterested contacts, make the email we use for sending, the related domain used for the email and the public IP of the server itself perceived as untrustworthy and therefore the sent communications will not reach their destination or will be marked as spam.

Therefore, even purpose-specific services such as Brevo, MailUP, TurboSMTP, etc., can block our account if our list contains too many addresses that do not exist or are rejected by the recipient. Bulk email sending is very sensitive, many ISPs can also block SMTP ports if they detect bulk email sending from a particular public IP.

It is therefore very important:

  1. Keep lists up-to-date and clean, especially removing emails that no longer exist, users who have requested to be removed, or who have not interacted with communications for a long time.
  2. Do not send all emails in bulk, stagger sending to small blocks of users. Targeting them better, dividing our list into multiple lists based on purchases made or other parameters. If we send 10,000 emails in a few minutes, our own ISP may block the SMTP port for suspicious activity.
  3. Always check the statistics especially the reports regarding emails not reaching their destination.

Regarding point 2 and 3, ideally we can also figure out the best time to send our communication email to certain lists, it can make a huge difference, when and where our email is read.

These tips apply not only to email but to any method of sending, even sending via SMS or WhatsApp, are subject to the same issue, for example if we send a lot of messages to non-existing WhatsAPP users or many of them mark us as unwanted, we could have our account banned for life from the service, with no chance to recover it.

So to recap, this is not a GDPR issue. Our own communications if interpreted as harassing, can achieve the opposite effect, disincentivizing purchase on our ecommerce, because we then tartass with advertisements and offers. Many users to try new services, but also for the first purchase, use temporary emails that then expire and increase the bounce rate, we have talked about the problem here.

Author: Loris Modena

Loris Modena

SENIOR DEVELOPER

Per Ind Loris Modena owner of Arte e Informatica, began working in the computer industry in 1989 as a systems engineer in charge of maintenance and installation of computer systems. He starts programming for the web in 1997 dealing with CGI programming in PERL and later moving to programming in PHP and JavaScript. During this period he approaches the Open source world and Linux server management.

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