The EmailValidly guides
Start here: How to verify an email address →
Understand the result.
Make the next step clear.
Practical guides for verification, list cleanup, mail routing and developer integrations. Start with a problem, then use the relevant tool.
Provider-specific guides
Gmail address verification: what you can actually check
A Gmail address can have valid formatting while its mailbox status remains unknown. Start with the address and domain, then treat any mailbox response as limited evidence. Gmail ownership can only be established through a flow that the user completes with access to the account.
Outlook address verification for consumer and business email
Outlook is used for both consumer email and business mail experiences. An address may use outlook.com, another Microsoft consumer domain, or an organization’s custom domain. Verify the actual domain instead of assuming that every Outlook user has the same address rules.
Email plus addressing: preserve tags without making assumptions
Plus addressing adds a tag to an email local part, like alex+receipts@example.com. It is often used to organize incoming mail or distinguish signups. Whether it is supported depends on the receiving system, so it should not be treated as universally invalid or universally interchangeable.
Dots in Gmail addresses: safe deduplication boundaries
Google states that dots do not update the destination for consumer Gmail addresses. That is a provider-specific behaviour, not a universal rule for email. Applying it to every domain can merge different recipients and damage a contact database.
Verification basics
Email validation vs verification vs ownership confirmation
These terms are often used interchangeably, so compare the checks rather than the product label. A syntax validator, a mailbox verifier and an ownership-confirmation flow answer different questions. A good implementation keeps all three meanings visible.
Email verification accuracy: how to evaluate the evidence
An accuracy percentage is difficult to interpret without knowing the test set, the definition of a correct result and the treatment of unknowns. Evaluate a verifier against decisions in your own workflow, not just a single headline number.
Unknown email verification results: a safe retry and review policy
Unknown means the check did not establish a conclusive answer. It is not a softer spelling of invalid. A useful workflow preserves the reason, decides whether a retry is worthwhile and avoids turning missing evidence into a confident claim.
How email verification works: the checks and their limits
Email verification combines several observations about an address. Each observation answers a different question. A useful result explains which checks passed and which remain uncertain, instead of treating every reachable domain as a confirmed inbox.
SMTP email verification: what a mailbox probe can tell you
SMTP verification inspects how a receiving mail server responds to an address. It can provide a useful signal, but it is a conversation with a mail system, not a login to someone’s inbox. Many systems intentionally make the answer inconclusive.
What is a catch-all email domain?
A catch-all email setup accepts mail addressed to otherwise unmatched names at a domain. That can be convenient for a business, but it makes individual mailbox verification less conclusive. Catch-all describes routing behaviour; it does not identify an inbox owner.
How to check if an email exists without overstating the result
You can check an address’s format, its domain and its receiving infrastructure. You may also obtain a mailbox response. Those checks can rule out some errors, but they cannot always establish that a specific inbox exists or belongs to the person you expect.
Can you verify an email address without sending an email?
Yes, you can run useful technical checks without sending a message. Syntax, DNS, disposable-domain detection and optional SMTP probing can show problems. The limit is certainty: a check without a delivered confirmation cannot prove that the intended person controls the inbox.
Bounce troubleshooting
SMTP 550 errors: distinguish recipient failures from policy blocks
A 550 response indicates a failed SMTP action, but the number alone is not enough to identify the fix. Read the full diagnostic text and the stage at which it occurred before deleting a contact or changing your sender setup.
SMTP 450 errors: handling a temporary mail failure
A temporary SMTP failure calls for controlled retry behaviour and investigation of the accompanying reason. It should not immediately become a permanent invalid-address label in your database. Start with what the delivery system actually reported.
Why emails bounce: a practical diagnostic workflow
A bounced email is a delivery failure reported by a mail system. The reason may involve the recipient, the destination domain, the message or the sender’s configuration. Start with the actual delivery report; checking the address alone cannot explain every bounce.
Hard bounce vs soft bounce: what to do with each
Hard and soft bounce are operational labels for permanent-looking and temporary-looking delivery failures. The label is useful, but the original response and your sending provider’s classification matter more than the colour of the badge.
DNS and authentication
Null MX records: when a domain explicitly accepts no email
A null MX record is an explicit DNS declaration that a domain does not accept mail. It is different from an empty MX lookup or a temporary resolver error. That distinction matters when interpreting verification results or configuring a domain used only for a website.
SPF, DKIM and DMARC: what each email-authentication layer does
Email authentication concerns the sender’s identity and message handling. It is not the same as verifying a recipient address. A domain can receive mail correctly while its outgoing messages have authentication problems, so inspect the correct side of the conversation.
SPF DNS lookup limits: diagnose the evaluated policy
An SPF policy can become difficult to maintain as more sending services are added. Counting the visible include statements is not enough to understand its evaluation. Nested policies and the actual matching path matter, and a plain TXT lookup cannot certify the whole result.
DMARC alignment: why a passing signature may not be enough
Alignment relates an authenticated domain to the domain shown in the message’s From identity. It explains why a message can show a passing authentication result yet still fail DMARC. Diagnose the identities used by the actual message rather than looking only for a published DMARC record.
What is a DKIM selector, and where do you find it?
A DKIM selector identifies the public-identifier record used with a signing domain. A domain name alone is generally insufficient to know which selector an actual message used. Start with the sender’s setup instructions or the signature on a message you are authorised to inspect.
What is an MX record? How to read mail-routing results
An MX record identifies a mail exchanger for a domain. It tells a sending system where to attempt email delivery. An MX lookup is therefore a domain-level routing check, not a directory of individual mailboxes.
List quality
Email domain typos: suggest corrections without changing recipients
A small domain typo can send a message to the wrong place or make delivery fail. A good typo workflow offers a correction while preserving the user’s original input. It does not silently turn a plausible guess into a confirmed destination.
Email list hygiene: a repeatable cleanup process
List hygiene is the process of keeping contact data usable and its sending rules intact. Verification is one step. Duplicates, stale records, consent and suppression history need separate handling so a technically valid address does not become an excuse to send the wrong message.
How to clean and verify an email list CSV
A reliable CSV workflow starts by choosing the correct column and ends by reconciling every row. Do not use a broad email-extraction regex as a substitute for parsing a tabular file: it can pull addresses from details, hide malformed entries and lose the relationship to the original records.
Email suppression lists: keep sending restrictions through cleanup
A suppression list records destinations that should not receive a particular sending stream. It is different from a list of syntactically invalid addresses. Keeping suppression separate prevents a new import or a passing verification result from undoing an existing restriction.
Temporary email domains: detection without overblocking
Temporary email services provide addresses that may be short-lived, publicly accessible or designed for limited use. Domain detection is useful for assessing this risk, but it should be one part of an application policy rather than a verdict about the person entering an address.
Developer guides
Email verification in Python with safe retries
A useful Python integration treats verification as a tabular, billable operation. Keep the Api token on the server, use an request identifier tied to the logical job and preserve unknown results. A network exception should not cause a new charge simply because the client generated a new identifier.
Email verification in JavaScript: server-side integration
Call the authenticated verification API from your server, not from public browser JavaScript. That keeps the identifier private and gives your application control over credits, retries and data handling. Browser-side syntax checks can still provide immediate feedback before the server request.
Email validation regex: useful checks and common traps
A regular expression can catch obvious input errors, but it cannot verify a mailbox. Treat regex validation as a form-handling decision with a defined compatibility scope, then use server-side checks and confirmation where the application needs more evidence.