So what does email deliverability or inbox deliverability rate mean? More importantly, what can you do if yours is not acceptable in order to improve your overall email campaign performance? In this section, we'll discuss what an acceptable email deliverability percentage is, what it may imply about your email marketing efforts, and what actions you can immediately take to attempt to improve this metric.

Email Deliverability Numbers Defined

As we previously mentioned, your email deliverability rate is the number of emails that you sent that were successfully delivered to recipients. It is not a reflection of whether your email went into the spam or junk folder of your recipient. As long as your email is delivered, it is counted as a positive delivery no matter what folder it is placed in by the email service provider. Emails that are not delivered may be email addresses that do not exist and were entered into your system improperly, email addresses that have been cancelled or deactivated since your last send, email addresses where the email service provider is experiencing technical difficulties at the time of your email send, or email addresses where the recipient's email account was full and could not receive further messages. Essentially, any email for which a viable destination account was not found is listed as an undeliverable email.

Desirable Email Deliverability Numbers

Of course, you want your email deliverability bounces to be as low as possible and as close to zero as possible! In reality, no matter how diligent you are about maintaining a clean email list ; bad addresses may slip through or be added to your email marketing list, which then causes trouble with your email deliverablity.

If your email deliverability bounces exceed three percent, then you have entered a red flag zone. You are within normal parameters if the undeliverable count is between one and two percent.

What Your Email Deliverability Numbers Say About Your Email List

If your email deliverability bounces are too high, this may mean one of several things about your email list.

  • You are Not Properly Vetting Emails at the Time of Sign Up: You might be surprised how many people will mistype an email address when they enter it into a submission form. While some of this activity is unable to be controlled by you, there are some basic email checks that you can make sure are implemented at the time of sign-up. Making sure that all emails meet the basic format of using a "@" sign and ending in an ".extension" format can reduce the number of bad addresses entered into your email system.
  • You are Not Regularly Pruning Your Email List: Earlier in this book we discussed the process of pruning and cleaning your email list, which is the process of making sure that bad email addresses are regularly removed from your email list after they have bounced several times. If your email deliverability percentage is too low (or your undeliverable percentage too high), you should check to ensure that your list is being regularly and actively pruned.
  • You Have Malicious Competitors: It can be a mean world out there. It's not entirely impossible that if you see a high and unexpected amount of undeliverable emails that your competitors have taken to a black-hat technique of spamming your email sign-up list with poor quality addresses in order to decrease your sender reputation.
  • You Have Rented or Purchased a Bad List: If the list of emails that you have sent to is a rented, purchased or traded list, then you can be assured that the list was not properly scrubbed before you obtained it. One of the risks of purchased or rented list is that you may ultimately get a high number of bad our bounce addresses.
  • You Ported Emails Over From Another Source Without Controlling for Old Addresses: If you created your email list by porting email addresses over from another email source location, such as your retail database, but didn't have the list scrubbed or cleaned before you sent an email, you will experience a high undeliverable count. Because databases that do not send email frequently do not have to be concerned with pruning or cleaning, you may have a high number of bad addresses.

If you are seeing a high number of undeliverable emails (or a low email deliverability rate number), it most likely means that you are experiencing one of the above situations. It's imperative that you remedy the situation, as a high undeliverable count can significantly damage your sender reputation.

What Can You Do To Improve Your Email Deliverability Numbers?

Fortunately, most of the issues and problems indicated by a high number of undeliverable email addresses can be remedied over time.

  • Error Checking: If you are not checking for email format when a user submits his or her email to your list or database, add error checking for basic email format including "@" and ".extension." • Switch to Double Opt-In: If you are using a single email opt-in method for email sign-ups, switch to a double opt-in. If a user has entered a bad address, non-existent address or mistyped address (or even an intentionally bad address for malicious reasons), he or she will not receive their confirmation email. Without that confirmation email, the individual cannot activate their email send and you will not be penalized for the bad or undeliverable address in your database.
  • Double Check Pruning Procedures and Settings: If you are using a third-party email platform such as Comm100, check to ensure that your pruning settings are set correctly, typically to remove addresses after three to five bounces. If you are using an in-house proprietary email system, run a number of tests to ensure that your list pruning is and has been happening effectively and on-time.
  • Be Wary When You Buy or Rent a List: If you are purchasing or renting an email list, be sure to negotiate an appropriate or acceptable number of bounced addresses from the list and ensure that you will get financial compensation for any bounced addresses over the agreed upon limit. No email list is perfect, so do not expect a zero percent bounce rate. Aim for an acceptable one to two percent bounce rate, though you may need to stretch to three percent in some instances. Always be responsible about doing consumer research about any organization that you rent or purchase an email list from.
  • Be Wary of Porting Contacts Over: If, in any instance, you are transferring email addresses from one portion of your database into your email marketing list, take appropriate precautions. Write a script to do a basic remove of any addresses that are not in proper email format. You may also want to separate emails by the age of the entry in your database and send in segments with newer addresses first. Older addresses are likely to have a higher percentage of bad addresses, and by sending them separately you may be able to target and remove them more quickly.

Keeping a clean email list that can get high email deliverability is important to not only preserving your sender reputation but also to providing you with realistic email marketing metrics based on a viable list rather than an inflated one. Pay attention to your email deliverability metrics and you'll be rewarded with improved overall email list activity.

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