Florin Armasu, CEO and founder of Data Innovation and creator of the Sendability platform, has spent fifteen years managing email infrastructure for brands like Nestle and Brown-Forman. In a conversation with Sophie Steffen for The Open Rate Club, he took a crowbar to the received wisdom on list hygiene – specifically, the widespread assumption that aggressive purging is always the right answer. His position is more nuanced, more practical, and almost certainly more profitable.
The Double Opt-In Trap Nobody Talks About
Double opt-in is the default recommendation for list building. It is safe. It is compliant. It is, by virtually any compliance framework you care to name, the correct thing to do. It also has a failure mode that the people recommending it almost never mention: if your sender reputation is already damaged, the confirmation email itself lands in spam.
Consider the circularity of this. You are implementing double opt-in specifically because you want a clean, high-quality list. But the mechanism that confirms new subscribers depends on your ability to reach their inbox. If your reputation is poor – which is often why you are implementing stricter list hygiene in the first place – the confirmation email goes to spam, the subscriber never confirms, and you lose them before they have received a single piece of actual content. You are building a wall around your list using the very bricks that are crumbling.
The alternative, as Armasu describes it, is single opt-in combined with email verification at the point of registration and honeypot fields to catch bot signups. A honeypot is a form field that is invisible to human users but visible to automated scripts. When a bot fills it in, you know the signup is not real, and you discard it. This catches the most common source of junk signups without requiring a confirmation email that may or may not arrive.
The Three Buckets (and the One Nobody Knows What to Do With)
Most email verification tools classify addresses into three categories: valid, invalid, and a gray area of uncertain results. Valid addresses get mailed. Invalid addresses get removed. The gray list – the uncertain middle – is where the interesting decisions happen, and where most of the bad advice lives.
The standard recommendation from compliance-minded consultants is to purge the gray list along with the invalids. Armasu’s counterpoint is blunt: user acquisition is expensive, and throwing away 80% of your database because a verification tool could not give you a definitive answer is not prudence. It is waste.
“Don’t be mad about it. Don’t eliminate everybody. You just give yourself a chance ‘cause you invested in acquiring that user.”
The gray list problem is particularly acute with catch-all domains – mail servers configured to accept messages to any address at that domain, regardless of whether the specific mailbox exists. Verify sophie@yahoo, sophiesteffen@yahoo, and sophiesteffen2048@yahoo, and all three return the same result: “okay for all.” The verification tool has performed its check and told you precisely nothing. The only way to resolve these addresses is to actually send to them and monitor the bounces – which requires infrastructure-level bounce tracking that most ESPs do not expose in sufficient detail.
The Practical Approach: Send, Monitor, Then Decide
Armasu’s method for handling the gray list is to separate the clearly invalid from the uncertain, send to the uncertain, and let the mailbox providers themselves tell you which addresses are real. When you send an email and the recipient does not exist, the receiving server returns a bounce. That bounce is a definitive signal – far more reliable than any pre-send verification check – and it tells you to remove the address immediately.
The key insight is that mailbox providers are already doing the verification that your third-party tool attempted and failed. Gmail knows whether an address exists. Hotmail knows whether an address exists. They will tell you, in the form of a bounce, with perfect accuracy. The pre-send verification is a probabilistic guess. The post-send bounce is a certainty. The question is whether you are willing to send one email to find out – and whether your infrastructure can handle the bounce processing quickly enough to suppress the address before the next campaign.
This requires a level of infrastructure sophistication that most marketers do not have. You need real-time bounce processing, per-address suppression, and the ability to act on bounce data between campaigns rather than discovering three days later that 12% of your last send was hard bounces. Armasu has built this into the Sendability platform. Most commercial ESPs handle it with varying degrees of competence and transparency.
Spam Traps: The Risk You Cannot Afford
The pragmatism has limits. A Boston Consulting Group study that Armasu references identifies poor list hygiene as one of the most significant deliverability risks, and the specific threat is spam traps. A spam trap is an email address operated by a mailbox provider or anti-spam organization specifically to catch senders who are mailing to addresses that should not be on any legitimate list. Some are recycled addresses – real accounts that were abandoned and repurposed as traps after a period of inactivity. Others are pristine traps – addresses that were never used by a real person and exist solely to catch senders who obtained them through scraping, purchasing, or other illegitimate means.
Hitting a spam trap does not generate a bounce. It does not generate a complaint. It silently registers as a reputation hit with the trap operator, and if you hit enough of them, your sending infrastructure gets blocklisted with the quiet efficiency of a bureaucracy that does not need to explain itself to you. This is why cleaning matters – not as a moral exercise, but as a defense against the specific mechanism that can destroy your sending reputation without any visible warning.
The balance, as Armasu frames it, is between two risks: the risk of purging too aggressively and losing legitimate subscribers you paid to acquire, and the risk of purging too little and hitting spam traps that silently erode your reputation. The correct position is somewhere in the middle – clean the clearly bad, test the uncertain, and monitor everything with the sort of per-provider granularity that tells you whether your Hotmail reputation just took a hit before it becomes a blocklist.
The Compliance Trap
There is a broader philosophical point underneath the list hygiene debate, and Armasu states it plainly. The email industry has developed a tendency to treat deliverability as synonymous with compliance – a set of rules to follow rather than a set of outcomes to optimize. The compliance mindset says: purge aggressively, never mail anyone uncertain, follow every guideline to the letter, and if your list shrinks to nothing in the process, at least you were compliant.
The problem with this approach, as Armasu puts it with the sort of deadpan clarity that suggests he has had this argument many times, is that the logical endpoint of perfect compliance is sending zero emails. Zero emails means zero complaints. It also means zero revenue, which is the sort of outcome that tends to resolve the deliverability question permanently by eliminating the need for a deliverability team at all.
The practical alternative – what Armasu calls “profitable deliverability” – treats the email list as a revenue-generating asset that needs to be managed, not a liability that needs to be minimized. You clean it because spam traps are real risks. You do not incinerate it because a verification tool returned a question mark.
For the full interview breakdown, see our complete Expert Insight with Florin Armasu.
Tools Mentioned in the Interview
The following tools and platforms were referenced during this conversation.
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