Why Early Validation Matters
Inactive contacts are a normal part of email marketing. Even your most loyal, high-value customers will have periods of inactivity—often as much as 80% of the time. What harms your email program most isn’t ordinary inactivity, but the presence of completely inactive contacts and especially ‘zombie’ addresses: emails that enter your list with only superficial signs of life, like opens, but remain inactive and contribute no real value.
These are the silent killers of your engagement, harm deliverability, and even introduce compliance risks. Identifying and removing them requires a proactive approach, starting from the moment a contact enters your system. By focusing on validation earlier in the data lifecycle, you can build healthier lists, get better results and reduce the risk of long-term issues.
The Changing Email Landscape
The rules of email marketing are shifting slightly to accommodate technological and privacy-driven changes. Tools like Apple’s Mail Privacy Protection obscure open tracking to identify engagement, making it harder to distinguish genuine engagement. At the same time, the use of temporary email addresses and aliases is getting easier with “Hide my Email” provided by Apple, and apparently soon to come “Shielded Email” for Android users from Google (apologies for this source link: you have to deselect 15 different “Legitimate Interest” tracking cookie options).
The increase of temporary alias addresses and the challenges in accurate engagement tracking have led to more ‘zombie’ addresses stagnating in lists, quietly undermining campaign results.
The Legal Imperative
Data protection regulations like GDPR require that data be kept accurate and up-to-date, and that inaccurate data is deleted (ref: GDPR Art5(1)d). Data hygiene is not just best practice—it’s essential for compliance. From a legal standpoint, waiting until the end of the data lifecycle to address these issues is no longer an option.
Why Early Validation is Essential
Early validation catches issues before they become problems, protecting sender reputation and improving engagement rates. By catching invalid, inactive, or temporary addresses upfront, marketers can:
- Prevent low-quality data from affecting email deliverability.
- Quickly identify the risk of bot attacks and spam sign-ups.
- Ensure your messages reach real, engaged recipients.
- Increase ROI with improved campaign results, from lower volumes
Spam Complainers
Gmail and iCloud, and the default mail apps in Android and iOS do not send “feedback loop” unsubscribe requests to senders when an email is marked as junk or spam. This means most spam complainers will stay on the list - especially when the initial email delivery was marked as an “open”, and the sender marks “openers” as “active” for months or even years.
Insights from Deliverability Reviews
New sign-ups are usually among the most active contacts in a list. However new sign-ups also contain invalid and inactive contacts. These are made up of
- Typos - often a valid address, but the wrong recipient
- Deliberately-fake addresses, again potentially valid, deliverable address
- Temporary email addresses and aliases
- Bot sign-ups
- Bundled and Coerced opt-in, where a new account signup forces or hides marketing opt-in
- …and valid sign-ups who have not engaged with your Welcome Programme and marketing
The ‘zombie’ addresses, mentioned earlier, happen when there is typo or (fake, bot or bundled sign-up); then a ‘machine open’ falsely marking the contact as ‘active’; and the recipient marks the unwanted email as junk.
All emails go to the junk folder, but because of the false “open”, the sender keeps them in the list for months or years. These ‘zombie’ addresses don’t bounce but provide zero engagement or value while they are in the list. And this is an increasing cause of the Deliverability issues I see.
Through my work analyzing email data, I’ve observed that a typical mailing list will contain around 5-10% of inactive new sign-ups, with even the very best lists containing 2-3% of these zombies.
The real “red flag” however, is when more than 10% of a contact list is made up of inactive, new contact data. This signals underlying issues such as:
- Flaws in the sign-up process, allowing invalid or temporary emails.
- Bot attacks or fraudulent sign-ups introducing bad data into the list.
- Ineffective welcome campaigns failing to engage subscribers.
- And in some countries; purchased data.
Some email programmes wait years before deleting contacts, if at all (especially if there has been an “open”). It is rare to see a marketing team actively monitoring inactivity rates, so inactive data is not usually looked at until there are deliverability issues.
Solutions for Proactive List Management
Traditional methods like double opt-in (DOI) remain valuable but do not give complete protection. To address the challenges of today’s email landscape, a more complete approach is needed.
Real-Time Validation
Verify email addresses at the moment they’re entered on a form, webpage, or point of sale. Real-time validation catches typos, spam traps, and disposable addresses before they enter your system, ensuring only high-quality data makes it into your list. But as well as list protection, it also allows your customer to correct the email address as part of the process, meaning the sign-up is not lost.
First-Click Confirmation
Unlike traditional DOI, first-click confirmation keeps new subscribers in an “unconfirmed” state until they click a link in their emails. The link click confirms the status of the contact without risking the friction and drop-off rates often associated with DOI. This can be coupled with email reminders to confirm the address by clicking a link, and also in your website or app, the ability for the address to be corrected or updated
Clean Start Validation
Clean Start Validation, combining real-time validation and first-click confirmation into a single, streamlined process. This hybrid approach ensures every new contact is high-quality and engaged while avoiding the downsides of relying on either method alone.
Combining real-time and first-click confirmation of new sign-ups, Clean Start Validation:
- Prevents bad data from entering your list.
- Improves compliance with data protection regulations.
- Increases deliverability and engagement rates by focusing on genuine subscribers.
- Removes restrictions and risks of traditional DOI
Summary: Validate, then Confirm for Email Success
In a world of evolving technology and privacy standards, list management needs to evolve.
Clean Start Validation, combining real-time validation and first-click confirmation ensures your email lists are correct and compliant from the moment new contacts enter your system; building cleaner, more engaged lists that drive meaningful results from day one.