Precision over promises.
We started Qualisend because a verification result should be something you can trust - and actually understand.
Most tools hand you a label and hope you don't ask how they got there. We do the opposite: every address comes back with a plain verdict and the reason behind it - no mystery, no optimistic rounding.
That matters because the expensive mistakes in email are the confident ones. A verifier that calls an unconfirmable address “valid” hasn't saved you a bounce; it has moved the bounce to your next campaign, where it costs reputation instead of a credit. We would rather tell you we don't know.
So the product is built around evidence you can read: a verdict, a reason code, the flags that apply, and what the mail server actually said. The same detail our own team would want if they were debugging your list.
What we believe
Evidence beats a score
A number out of 100 with nothing behind it is a guess wearing a suit. Every verdict ships with its reason, its flags, and the provider detail, so you can check our work instead of trusting it.
“Unknown” is an answer
Mail servers greylist, rate-limit, and go quiet. A tool that returns a confident verdict every time is describing a network that doesn't exist. We return unknown and tell you to retry.
Your lists stay yours
We don't sell, rent, or share the addresses you upload, and we don't use them to train models or enrich anyone else's results. Delete a job and its results whenever you like.
Honest about limits
A catch-all domain accepts every address, so no tool can confirm a mailbox behind one. We report those as risky rather than dressing them up as deliverable.
How a verdict is made
Behind each result is a pipeline: syntax, domain and MX checks, disposable and role detection, then a real SMTP conversation with the receiving server. What comes back is one of four statuses - deliverable, risky, undeliverable, or unknown - plus the reason code that explains it.
What we build
Verification
One address or a million, in the dashboard, over the API, or through a connector to the tool your list already lives in.
Deliverability tooling
Authentication, DNS, and reputation checks, so you can fix the cause of a bounce instead of just counting it.
Blacklist monitoring
Your domains and mail IPs checked against 40+ lists continuously, with an alert the moment a listing appears or clears.
Built to plug in
Integrations with the platforms you already use, a documented REST API, and an MCP server so an AI agent can verify a list in plain language.
What we publish
Most of what we know is free to read. Tools that run without an account, in-depth articles, a plain-language glossary, and setup guides for the providers people actually send from - in five languages. We try to write the guide we wanted when we were debugging our own deliverability: sourced, specific, and willing to say when the honest answer is “it depends”.
Talk to our team
Questions about a verdict, volume pricing, or whether we fit your stack - one inbox, answered by the people who build the product.