The common patterns
Company directories — Google Workspace, Microsoft 365, an HR system feeding either — generate addresses from a template. The template is almost always one of these, in this order of popularity: first.last, first, flast (first initial plus surname), firstlast, first_last, f.last, last. A long tail of a dozen others — last.first, firstl, fl, hyphenated forms, middle-initial forms — covers the rest. The percentages below are base rates across large samples of company domains.
What the format tells you
The top three cover about two thirds of companies; the top five about three quarters. That is the arithmetic behind guessing: three verified guesses find the address at most companies, and beyond five the odds per additional guess drop under 4%. The format also correlates with company size and age — first alone is a small-company habit that collides at fifty employees, first.last is the default for anything larger, and flast and firstl are common in older enterprises and finance where addresses were once capped at eight characters.
How to find a company's format
One real address is the whole answer. Look on the company site for a contact page with a personal mailto:, PDFs with author lines, press releases with a media contact, speaker bios, GitHub commits by employees. Any one of those gives the format. Then apply it to every other name at the domain. The permutator does this in one step in bulk mode: pick the known format and every row gets one address.
How names are normalised
Directories lower-case, strip accents and remove spaces, apostrophes and hyphens: Zoë O'Brien becomes zoe.obrien, Jean-Luc becomes jeanluc. Middle names are usually dropped; some enterprises keep the initial. Double-barrelled surnames are the most common failure — try with and without the hyphen and with only the first part. Nicknames are a lost cause: the directory has the legal name.
The limits
The format gives you a candidate, not a mailbox. It has to be verified against the mail server before it goes near a sequence, and about one company domain in five is a catch-all where verification cannot confirm anything. Free-mail providers have no format at all — people take whatever local part was available — so guessing there is pointless and expensive.
Check yours
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Common questions
What is the most common email format?
first.last@company, at roughly 35–40% of companies. first@ is next at about 15%, then flast@ at about 12%.
Do companies ever use more than one format?
Rarely on purpose. It happens after mergers, when two directories are joined, and in very old companies where early accounts predate the template. Assume one format until you see evidence of two.
How do I handle hyphenated or accented names?
Strip accents, drop apostrophes, and try hyphenated surnames three ways: joined, first part only, and with the hyphen. Directories differ on hyphens more than on anything else.
Does knowing the format mean the address exists?
No. The person may use a different domain, a nickname, or have left. Verify every candidate before sending.
Related concepts
If this is the thing going wrong
The pages explain it. If you would rather it was simply fixed, that is the work I do.