Bad data is one of the quietest ways outbound fails. Emails bounce. Sequences land in front of the wrong people. Sender reputation degrades without any obvious reason. And because none of it happens loudly, it often goes unnoticed until the damage is already done.
Data hygiene is the process we run to make sure none of that happens on your campaigns.
Why it matters more than most people think
Most outbound tools will let you upload a list and start sending without checking anything. That is a problem.
A list with a 10 percent bounce rate will damage your sender reputation within weeks. A list with outdated job titles means your personalisation is wrong before the email even gets read. A list with duplicates means some contacts get the same email twice, which looks unprofessional and can trigger spam complaints.
None of these things are dramatic on their own. Together they quietly make your outbound perform worse every week.
What we check on every list
Before any contact enters an active sequence we run four checks.
Deduplication removes any contact that appears more than once. This applies within a single list and across multiple lists if you are running more than one campaign at the same time. The same person should never receive two emails from the same campaign.
Normalisation standardises how data is formatted across every field. Names, job titles, company names, and domains all get cleaned to a consistent format. This matters because inconsistent data breaks personalisation tokens inside your sequences and can produce visible errors in the email itself.
Email validation verifies that every email address on the list is active and deliverable before we send to it. We flag catch-all addresses separately and treat them with more caution since they accept any email but may not forward it to a real inbox.
Domain validation checks that the company domain is active and not associated with any known spam traps, honeypots, or flagged domains. Sending to flagged domains is one of the fastest ways to get your sender reputation damaged.
The suppression check
On top of the four standard checks we run every list through a suppression layer before any outreach begins.
This cross-references your contact list against anyone who has previously unsubscribed, opted out, asked to be removed, or been marked as do not contact across any of your previous campaigns.
We cover this in more detail in the Suppression Layer article, but the short version is that no contact who has ever asked not to be contacted will receive an email from your campaigns. This protects your reputation and keeps you compliant.
How we handle problem records
Not every record that fails a check gets discarded. We triage them.
Records with undeliverable emails go into a re-enrichment queue. We attempt to find an alternative verified address through our data provider waterfall. If one is found the record gets updated and moves to the active list. If not it gets marked as unreachable and excluded from sequences.
Records with missing or incomplete data get flagged for manual review before being activated. We would rather hold a record back than send an email with a broken personalisation field.
Records that fail the domain validation check are removed entirely and flagged so the same domain does not appear on future lists.
Ongoing hygiene after launch
Data hygiene is not a one-time process. Lists degrade over time as people change jobs, companies rebrand, and email addresses go stale.
We run a hygiene pass on every active list as part of the weekly refresh cycle. Bounced records get removed immediately. Records showing job change signals get updated. New contacts added to the list go through the full check process before they are activated.
The goal is that your list quality stays consistent or improves over the life of the campaign, rather than getting worse the longer it runs.
FAQ
What is an acceptable bounce rate?
Industry best practice sits below two percent. Above five percent and your sender reputation starts to take meaningful damage. Above ten percent and most email providers will begin throttling or blocking your sends. We aim to keep bounce rates below one percent on every campaign we run.
What is a catch-all email address?
A catch-all is a domain configured to accept any email sent to it, even if the specific address does not exist. This means validation tools cannot confirm whether the address is real. We flag catch-all addresses separately and typically send to them at lower volume with closer monitoring of the bounce signal.
Can you clean a list we already have?
Yes. If you have an existing contact database we can run it through the full hygiene process and tell you what the quality looks like. We will give you a clear breakdown of how many records passed, how many need re-enrichment, and how many should be excluded before sending.