TL;DR
A valid email address follows the pattern local-part@domain, with the local part capped at 64 characters and the full address capped at 254. The most common B2B company format is first.last@company.com, used by roughly 60% of mid-market and enterprise teams.
To find any specific company's format, run the domain through a pattern detector or check public sources like press releases and GitHub commits. To verify a guess, run it through an email verifier that pings the mail server directly.
The standard parts of an email address
Every valid email address has the same shape. Two parts, separated by a single @ sign.
sarah.chen@stripe.com
The local part
The local part is everything before the @ sign. It identifies the individual inbox inside the company. The mail server at stripe.com knows how to route a message to the inbox named sarah.chen because it controls that domain.
RFC 5321, the technical spec that governs SMTP, caps the local part at 64 characters. In practice almost no real address gets close to that limit. Most local parts are 5 to 25 characters.
Valid characters in the local part include lowercase letters a to z, uppercase letters A to Z, digits 0 to 9, and the following symbols: period, hyphen, underscore, plus, ampersand, percent, and a few others. Spaces are not allowed without quoting. In B2B contexts you will see periods, hyphens, and underscores almost exclusively.
The @ sign
The @ sign separates the inbox name from the domain. It must appear exactly once. Any address with zero or more than one @ sign is invalid.
The domain
The domain is everything after the @ sign. It identifies the mail server that owns the inbox. Companies typically use their primary website domain, like stripe.com or google.com. Some use a subdomain like eng.company.com for specific teams.
Domain length is capped at 255 characters by RFC 5321, but the combined local part plus @ plus domain cannot exceed 254 characters total. So if you have a 50 character local part, you have 203 characters left for the domain.
Domains can contain letters, digits, hyphens, and periods. Hyphens cannot appear at the start or end of a label, and labels are separated by periods.
The 12 most common email format patterns at B2B companies
After analyzing millions of B2B addresses across our database, twelve patterns cover the vast majority of working email addresses at companies above 10 employees. Here they are in order of frequency.
first.last@
Example: sarah.chen@stripe.com
The dominant pattern at modern B2B SaaS companies, mid-market, and enterprise. It scales cleanly as the company grows because you almost never get a full first-and-last-name collision. New hires get their natural address without an admin negotiation.
Companies that use this: Stripe, Google, ZoomInfo, Salesforce, HubSpot, Notion.
first@
Example: sarah@linear.app
Common at early-stage startups and small teams under 50 employees. It is short, friendly, and easy to type. The downside is name collisions appear fast: the moment you hire a second Sarah, someone has to compromise.
Companies that use this: Linear, many YC-stage startups, design studios, boutique agencies.
flast@
Example: schen@oracle.com
First initial plus last name. Very common at legacy enterprise companies, financial services firms, and government contractors. The pattern dates back to early corporate email systems that prioritized short addresses for terminal sessions.
Companies that use this: Oracle, IBM, Cisco, Goldman Sachs, most big-four consulting firms.
first.l@
Example: sarah.c@figma.com
First name plus last initial. Sits between first.last@ and first@ in compactness. You see it most often at companies that started with first@ and migrated when the first collision happened. It is a graceful upgrade path that lets early employees keep something close to their original short address.
Companies that use this: Figma, some design tool startups, certain ecommerce brands.
lastfirst@ or last.first@
Example: chensarah@accenture.com or chen.sarah@accenture.com
Last name first. Common at large consultancies and law firms where directories are sorted by surname. Familiar to anyone who has worked in a corporate Outlook environment where the global address list defaults to last-name-first sorting.
Companies that use this: Accenture, Deloitte (some practices), several global law firms.
last@
Example: chen@founder.com
Last name only. Rare in modern companies but still found at family-owned businesses, single-founder consultancies, and very small partnerships. Same collision risk as first@ but skews toward older brand traditions.
Companies that use this: Small partnerships, boutique consultancies, family-owned firms.
f.last@
Example: s.chen@deloitte.com
First initial, period, last name. A more readable variant of flast@. Popular at European companies and certain US enterprises that wanted the compactness of flast@ but preferred the visual separation a period provides.
Companies that use this: Deloitte (some regions), KPMG, European banks, several pharma firms.
firstl@
Example: sarahc@walmart.com
Full first name plus last initial, no separator. Common at large retailers, logistics companies, and certain manufacturers where IT systems were standardized in the 1990s and never migrated.
Companies that use this: Walmart, several Fortune 500 retailers, some manufacturing groups.
first-last@
Example: sarah-chen@duckduckgo.com
Hyphen-separated first and last name. Functionally identical to first.last@ but uses a hyphen instead of a period. Often a stylistic choice from technical founders who wanted email addresses that look distinct from filenames.
Companies that use this: DuckDuckGo, certain privacy-focused tech companies, several open source organizations.
first_last@
Example: sarah_chen@intel.com
Underscore-separated. Rare in modern setups because the underscore is hard to dictate verbally and screen readers handle it inconsistently. You will still find it at some legacy semiconductor companies, certain government agencies, and a handful of universities.
Companies that use this: Intel (legacy accounts), some US government agencies, several university systems.
first.last@team.domain.com
Example: sarah.chen@sales.bigcorp.com
First name plus last name on a department subdomain. Used by very large multinationals where business units run their own mail infrastructure or were acquired and kept their original mail servers. Often invisible to outsiders because the main domain also accepts forwarded mail.
Companies that use this: Holding companies, large multinationals, conglomerates with autonomous business units.
Custom alias formats
Example: handle@company.com or nickname@company.com
Any address that does not follow a predictable name-based formula. Common at companies where employees pick their own aliases (often early hires of indie SaaS brands) and at companies that use chat handles as email addresses. Pattern detection will not reliably surface these. The only way to find them is to look at addresses the person has used in public.
Companies that use this: Indie SaaS, certain creator-economy brands, some agencies.
How to find a specific company's email format
There are four reliable methods. Pick the one that matches the data you already have.
Use a pattern detector tool
The fastest path. Enter the company domain into a tool like the Mailsfinder Email Pattern Detector. It looks up known verified addresses from that domain and returns the dominant format with a confidence score.
Most pattern detectors will tell you something like: "stripe.com uses first.last@ (98% confidence based on 4,217 verified addresses)." That confidence number matters. A 98% score means you can apply that format to any new name and trust the result. A 60% score means the company likely has multiple formats in parallel, so you should verify each candidate.
When to use it: Always. This should be your first move for any B2B company above 20 employees.
Check published addresses
Employees publish their real email addresses in more places than they realize. Check these sources for any known employee at the target company:
- check Press releases: The "media contact" or "investor contact" section often lists a real address with a real format.
- check SEC filings: Proxy statements (DEF 14A) list executive contact information including email.
- check GitHub commits: Engineers commit code with their work email as the git author. Run a search on github.com for the company domain.
- check Conference speaker pages: Conference websites often list a contact email for the speaker.
- check Academic papers and patents: Authors list their work email on the byline.
When to use it: When the pattern detector returns low confidence, or when you want a second source to confirm a guess.
Generate permutations
If you cannot find the format published anywhere, you can brute-force it by generating every common permutation for the target name and verifying each one. For Sarah Chen at stripe.com, the permutation list looks like this:
Doing this by hand is tedious and error-prone. The Mailsfinder Email Permutator generates the full list in one click. Then you pipe it into a verifier (see method 4).
When to use it: When the company is small enough that pattern data is thin, or when public sources turn up nothing.
Verify each guess via SMTP
Once you have a candidate address or a list of permutations, the final step is verification. An email verifier connects to the recipient mail server over SMTP, opens a session, and asks the server whether it accepts mail at that address. The server responds yes, no, or "unknown."
Run candidates through the Mailsfinder Email Verifier and it returns a status for each: valid, invalid, catch-all, or risky. The valid result is the correct format for that person.
One catch-all warning: Some company mail servers accept all incoming mail to any address at the domain (catch-all configuration). For these domains, SMTP verification cannot definitively prove a specific address exists. You need the pattern detector to narrow it down first, then send a low-stakes test message to confirm.
How to format a professional email message
Once you have the right address, the message itself needs to be formatted well or it will get ignored. A professional email has five parts. Get each one right and the whole thing reads tight.
1. Subject line
The subject is the only part most recipients see before deciding to open or delete. Keep it under 50 characters so it does not get truncated on mobile. Be specific, not clever. "Quick question about your Q3 SDR hiring" beats "Hey there" every time.
For deeper subject line strategy, see our guide to best cold email subject lines.
2. Greeting
Use the recipient's first name. "Hi Sarah," is the safe default for B2B contexts. "Hello Sarah," is slightly more formal. "Dear Sarah," reads as old-fashioned outside very traditional industries.
If you do not know the recipient's name, "Hi there," is acceptable. Never use "Dear Sir or Madam" or "To whom it may concern" in 2026. Both signal that you did zero research.
3. Body (use P-E-P)
The strongest cold email and follow-up bodies follow a three-part structure: promise, evidence, proof.
- circle Promise: One sentence stating the outcome you can deliver, relevant to the recipient's role.
- circle Evidence: One sentence showing why you can deliver it (a metric, a case study, a credential).
- circle Proof: One sentence asking for the next step (a 15-minute call, a reply, a link click).
Total body length: 50 to 90 words for cold outreach. 90 to 150 words for warm follow-ups. Anything longer is going to get skimmed at best.
4. Sign-off
"Best," "Thanks," "Talk soon," and "Cheers," all work for B2B. "Regards" reads slightly more formal. "Sincerely" is reserved for very formal contexts and feels stilted in 2026 outreach. Pick one and stay consistent across the thread.
5. Signature block
A clean signature has four lines: your name, your title and company, your phone or calendar link, your company website. That is it. Skip the inspirational quote, the giant company logo, and the eight social icons. Signatures over 150 pixels tall make the message feel like a sales blast.
Common mistakes to avoid
After watching teams run thousands of campaigns, the same handful of mistakes show up over and over. Avoid these and your deliverability stays clean.
Typos in the domain
A single character off in the domain sends your message into the void. Double-check that the domain matches the company website. The address gogle.com is not google.com.
ALL CAPS in the address
Email addresses are case-insensitive per RFC, but typing them in all caps in your To: field looks unprofessional and some older spam filters flag it. Stick to lowercase.
Sending to deactivated formats
When companies migrate from flast@ to first.last@, old addresses often forward for 12 to 24 months, then go dark. Pattern detectors using stale data will return formats that no longer reach a human.
Role-based pitfalls
Addresses like info@, sales@, contact@, and admin@ are role accounts. They get filtered aggressively, monitored by multiple people, and have low engagement rates. Avoid them in outreach unless you have no other path.
Treating freemail addresses as B2B
Gmail, Outlook, and Yahoo addresses for a decision-maker at a real company usually mean the person uses personal email for side projects. Sending B2B pitches there often violates CAN-SPAM and gets reported as spam.
Skipping verification
Sending to unverified addresses inflates your bounce rate. Anything above 2% bounces and your sender reputation craters across all your future sends. Always verify before adding to a sequence.
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