How finding differs from guessing
Every company has an address convention, and every "email permutator" spreadsheet exploits that: generate firstname.lastname@, f.lastname@, firstlast@, and hope one lands. The problem is that hope is not verification. The wrong guesses bounce, and mailbox providers count every bounce against your domain, so each bad guess quietly taxes every real email you send afterwards.
This finder works from confirmation, not convention. Candidate addresses are derived at the company’s actual domain and the result is checked against the receiving mail server before you ever see it. What comes back is a mailbox that exists, graded high or low confidence, not a pattern that might.
The distinction shows up exactly where it matters: in your bounce rate, on the campaign you have not sent yet.
Getting the domain right
The domain you search against decides everything, and it is the detail most searches get wrong. People move companies constantly, and subsidiaries, rebrands, and acquisitions mean the domain in an old CRM export is often not where the person reads mail today. A perfect find at the wrong domain is still a bounce.
Use the domain the company actually sends mail from, which is usually, but not always, the website domain. If you only have a profile and are unsure where someone works now, the LinkedIn Email Finder on this site starts from the profile instead and resolves the current employer for you before searching.
The tool is forgiving about format: paste acme.com, www.acme.com, a full URL, or a colleague’s email at the domain, and the hostname is extracted automatically.
Reading the result
A found address arrives with a confidence grade. High means the mailbox was individually confirmed by the receiving server. On catch-all domains, where the server accepts everything and a plain check proves nothing, Renidly cross-confirms the mailbox against the identity graph instead of guessing, and marks the catch-all condition on the result so you know exactly what you are holding.
A miss is reported as a miss. Some domains are locked down hard enough that no single pass can confirm a mailbox, and an honest empty result beats a fabricated address that torpedoes your sender score. In the API, a lookup that finds nothing is never billed at the price of a hit.
When one search at a time stops being enough, the same endpoint takes 1,000 queries per batch job: submit the list, and verified addresses stream back as they resolve.