Have you heard that phrase, “you’re only as good as your weakest link”? This can absolutely be applied to your email list. No matter how long you’ve been building your list, and how many engaged subscribers you have on it, if you don’t perform routine list cleaning to get rid of any potential spam traps or unknown users, then you’re putting your email campaigns at risk to be sent to the spam folder or blocked.
Let’s start with unknown users, as those are typically easier to understand. An “unknown user” is defined as an invalid email address in your database. These can be added to your list in a variety of ways, but the most common are simple fat-fingering (for example, someone typing in [email protected] instead of [email protected]) and people purposely giving you a false address. The simple way to get rid of unknown users from your database is to implement proper bounce handling rules. These addresses will bounce back, so as long as your processing bounces accurately and have hard and soft bounce rules in place, then they will eventually be automatically removed from your list.
However, if you have somewhat lenient bounce rules in place, those unknown users can cause trouble even before they are removed from your list. To the receivers, having a high number of unknown users on your list is a sign to them that you aren’t practicing proper list hygiene or collection. And this can lead to deliverability issues. Most ISPs will tolerate up to a 10% unknown user rate, but as you approach or exceed 10% you will likely experience delivery performance issues. We have found that our best senders with strong deliverability performance typically maintain an unknown user rate of less than 2%.
So what’s a marketer to do? As a first step, at initial sign up, ask a subscriber to confirm their email address by typing it in twice. Also, do an automatic, immediate check on all submitted email addresses to confirm they are in the [email protected] standard format. If you are collecting email addresses on the phone or at point-of-sale, have the associate repeat the email address back to the customer to ensure it is recorded correctly. Next, send that new subscriber an immediate welcome email. Any emails that bounce back from that initial communication should be removed from your list immediately. Also, consider sending this initial welcome email from a separate IP so that high unknown user rates from this mailing do not affect the deliverability of your other regular mailings.
To ensure invalid email addresses are being continuously removed from your list, implement proper bounce processing. Be sure to monitor your Reply-To address, establish hard and soft bounce rules appropriate to your sending practices, and ensure that bounces are appropriately categorized for processing as hard and soft bounces. Finally, put an on-going process in place to ensure you are regularly cleaning your list of old and inactive email addresses, as unknown users could also be email addresses that were once active but are no longer active by choice or were abandoned by the end user.
Now, let’s talk about spam traps. Spam traps are interesting and can be confusing because there are two different types. The first are referred to as “true traps” or “honey pots”. These are the spam trap addresses that were created specifically for the purpose of catching spammers. There is no live person behind a “true trap” so they will never actively subscribe to your list or take action on your emails. Spam trap operators will place these “true traps” to newsboards or even hide them in the code of a webpage where they can be scraped by spammers and added to lists.
The second type of spam trap are “recycled traps”. These are once-active email addresses that are no longer used by the original owner and have now been taken back by the ISP to use as a spam trap address. Typically, you will see these email addresses bounce as an unknown user first, then eventually will become active on your list again. There’s no set time between when these two events will happen – could be weeks, could be months – but it stresses the importance of cleaning your list of unknown users.
Obviously “true traps” are the most serious type, as they are indicative of list scraping and bad list practices. ISPs will put the most weight on these if they are hit and those will absolutely affect your email deliverability in a negative way. However, “recycled traps” can affect your deliverability as well, even though those email addresses did opt-in to your list at one point. Having a “recycled trap” on your list shows the ISPs that you are not practicing proper list hygiene.
Because I like to see the best in everybody, I’m going to assume that nobody reading this article has “true traps” on their lists. So let’s focus on “recycled traps,” because these are the kind I see my clients struggle with most. Once an ISP has taken back a once-active email address to be a spam trap, there will no longer be any activity (opens/clicks) from this email address. So, the trap address will be in the list of subscribers that do not open or click on your emails. Remember as well that you will typically see a pattern of previous bouncing with these addresses, so that can help you to narrow down even further.
From there, you have several options. You can send this group of inactive email addresses a re-engagement campaign, asking them to re-opt in to your list. You can send this as a series of campaigns, giving the subscribers multiple opportunities to re-opt in. At the end of that campaign series, anyone that has not re-opted in should be removed from your list, as the spam trap will be in this segment of your list.
Alternatively, another approach is to implement an IP segmentation strategy. Break your inactive group into several segments and mail to those segments on different IP addresses. With each send, you’ll be able to whittle down the segment that contains the spam trap address. Continue with this strategy until the segment is a more manageable size, and then either remove this segment from your list or run a re-engagement campaign as described above to this segment.
So remember, your email list is only as good as your weakest link. If that weakest link is a high unknown user rate or spam traps, then it’s time to take action now to save your email deliverability.