Verifying Guessed Email Addresses: How to Test first.last@ Patterns Before You Send
To use a guessed email address safely, generate the likely patterns for the person's name and domain, verify each one, and send only to the one that comes back "Mailbox exists". On domains that accept all addresses, no guess can be confirmed, so every candidate comes back risky with reason "Accepts all addresses" and you should not treat any of them as valid.
Step 1: get the domain right
The pattern only works at the correct domain. Confirm the company's mail domain from their website or a known address. A guessed domain that does not receive mail comes back with reason "No mail server". Typos are flagged, for example "Typo domain - did you mean gmail.com?" for personal domains.
Step 2: generate the candidates
For a person named Jane Smith at acme.com:
| Pattern | Candidate |
|---|---|
| first.last | jane.smith@acme.com |
| first | jane@acme.com |
| flast | jsmith@acme.com |
| firstlast | janesmith@acme.com |
| first_last | jane_smith@acme.com |
| lastf | smithj@acme.com |
The names are an example only. Email address patterns shows how common each format is and how to spot a company's convention from addresses you already have.
Step 3: verify every candidate
Put each candidate on its own row, keeping the name and company with it, and run the file. Do not skip candidates: you need the full set to see which one the server confirms.
Step 4: read the results
| Result | What it means | What to do |
|---|---|---|
| Mailbox exists (valid) | The server confirmed this mailbox | Use it |
| Mailbox not found (invalid) | The server says it does not exist | Drop it |
| Accepts all addresses (risky) | The domain takes anything | You cannot tell; see below |
| Role-based address (risky) | Shared mailbox, such as info@ | Skip unless you want a role |
| Server would not confirm (risky) | The server did not answer | Re-check once; see retry results |
Catch-all domains: where guessing stops working
A catch-all domain says yes to every address, including made-up ones. Every candidate at that domain looks the same, so the verifier cannot pick the right one. Sending to all candidates is a poor fix: wrong guesses may go to nobody, bounce later or reach a different person.
Your options on a catch-all domain:
- Look for the person's real address from a source other than a guess.
- Use the format of confirmed addresses you already have at that domain.
- Send a small test of your best guess and read the bounce rate before more.
Catch-all emails: what to do covers this in more detail, and accept-all vs unknown results explains why the two differ.
Cost to remember
One person with six candidates is six checks. For a list of 1,000 people that is 6,000 checks, so trim the patterns to the likely ones before running at scale. Cut candidates that other addresses at the domain rule out.
Plans and trial
New accounts get 100 free checks with no card, enough to test about 16 people at six patterns each. Pro is $39 a month, with the first 100,000 checks a month at full speed, then slower, never cut off. Business is $99 and Agency is $249 with 750,000 checks a month. See pricing, or try a candidate on the verify page.
Common questions
How do I find someone's email when I only have a name and a company?
Generate a few likely patterns at the company's domain, such as first.last@, first@ and flast@, then verify each candidate. The one that returns Mailbox exists is the address to use.
What if more than one pattern comes back valid?
Rare, but companies sometimes use aliases that deliver to one mailbox. Pick the format most others at that company use, or the one that matches published addresses.
What if every pattern returns risky?
The domain probably accepts all addresses, and no guess can be confirmed. The row is risky with reason Accepts all addresses. Test a small batch or find the address another way.
Is sending to a guess safe?
Only if a verifier confirmed it. A guess that is not confirmed may bounce, and a wrong but real mailbox may belong to someone else.
How many patterns should I try?
Start with the three or four most common, then add others only if the company's other addresses suggest a different format.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.