EMAIL VERIFICATION

Clean Every List With Real-Time Email Verification

Q: What is email verification?

Email verification is basically checking if an email address is real and active and ok to send to. It looks at the format first and then confirms the domain and MX records exist and then it checks if the mailbox actually takes mail. All of this happens before your campaign goes out.

Q: Why does every invalid address hurt my reputation?

If you send to an address that doesn't exist the receiving server gives you a hard bounce. Mailbox providers see a high bounce rate and they assume your list hygiene is bad or that you bought the data. So they start sending more of your mail to spam or they block it completely.

Q: What bounce rate is considered safe?

There's no one number that mailbox providers publish. A lower hard-bounce rate is always safer and a lot of deliverability teams try to stay under 2%. The easiest way to keep hard bounces out of your campaigns is to verify before every send.

Q: What does Warmy check for each address?

Warmy checks the syntax and formatting, whether the domain is valid, the MX records and whether the mailbox exists through SMTP. It also looks at catch-all domains and disposable or temporary addresses and role accounts like info@ or support@. On top of that it catches known spam traps and complainers.

Q: What are risky and unknown results?

A risky address might still be deliverable but verification can't be as sure about it as it is with a valid one. Things like catch-all domains and role accounts and mailboxes that haven't been active in a long time fall in here. Unknown just means the receiving server wouldn't confirm anything. You can drop both groups or send to them in a small separate segment.

Q: How often should I verify my list?

Verify new contacts when they come in. Any list you import or enrich or haven't emailed in a while should get verified again. Lists go stale because people switch jobs and stop using mailboxes so older data needs a new check before you send to it.

Q: Does verification work with my email platform?

Yes. Anything that lets you import or export a list will work. Klaviyo, Mailchimp, HubSpot, ActiveCampaign, Brevo, Customer.io, SendGrid, Amazon SES, Mailgun and dozens more and also custom SMTPs and in house systems.

Q: Can I verify addresses through the Warmy API?

Yes the Warmy API can verify a single address in real time when someone signs up or a full list in bulk. So validation can be part of your product flow and you don't need a manual step before every campaign.

Q: Will verification alone fix my deliverability?

No it won't. Verification takes away one of the biggest reasons for poor placement but your reputation also depends on authentication and warm-up and content and engagement. Warmy puts verification together with automated warm-up and seed-list placement testing and monitoring so everything moves at the same time.

Q: Is my contact data safe?

Yes. Lists are processed securely and they're only used to give you the verification results. Nothing gets shared or resold.

When you send to an invalid address you get a hard bounce and that hurts your sender reputation. Warmy's email verification tool finds those addresses before you even hit send.

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Warmy email verification dashboard with list validation results

List hygiene at scale

Stop Paying for Invalid Addresses Twice

You pay once to send to an address that doesn't exist. Then you pay again because that bounce pulls down your sender reputation for every campaign after it. Warmy's email list validation checks each contact before you send so your emails reach real mailboxes and your bounce rate stays low.

99.5%: Verification accuracy
<1%: Typical bounce rate after cleaning
Real time: Single and bulk checks
API: Verify at signup or in bulk

How it works

How Email Verification Works

Get rid of invalid and risky and inactive addresses before they cost you a bounce.

Upload or connect your list

Upload a CSV and Warmy pulls in the contacts you're about to email. You don't have to clean anything by hand.

Upload your contact list file for verification

Validated email list with deliverable and non-deliverable counts

Verify every address

Email address verification checks every contact and doesn't send any message. It looks at the syntax and the domain and MX records and then checks over SMTP if the mailbox is really there. It also finds catch-all and disposable addresses and role accounts and known spam traps and complainers.
Every address comes back as valid or invalid or risky or unknown so you can see what is ok to send to.

Send to a clean list

Export the clean list or push it back to your platform. Fewer bounces and complaints help your sender reputation and your inbox placement.

Any volume

Bulk Email Verification at Any Volume

You can upload a small test list or a full database and bulk email verification works on millions of addresses across Gmail, Google Workspace, Microsoft 365, Outlook, Yahoo, iCloud, Zoho and other mailbox providers.

10M+
Addresses verified per upload
1
Minimum list size to get started
Real time
Single checks via API at signup
99.5%
Verification accuracy at any volume

Trusted by teams sending at scale

What Warmy Checks on Every Email Address

Warmy runs a few checks to see if an email address is valid. It starts with the format of the address and then goes to the mailbox itself. For the mailbox check we ask the receiving mail server if it would accept mail for that address. We don't send a message.

Check	What it catches	Typical result
Syntax and format	Typos, missing @, invalid characters	Invalid
Domain and MX records	Domains that don't exist or don't accept mail	Invalid
Mailbox (SMTP)	Mailboxes that were deleted or never existed	Invalid
Catch-all domain	Servers that accept any address, so the mailbox can't be confirmed	Risky
Disposable address	Temporary inboxes that expire within hours or days	Risky
Role account	Shared addresses such as info@, support@, sales@	Risky
Spam traps	Known addresses used to catch senders with poor list hygiene	Invalid
Complainers	Addresses known for frequently marking mail as spam	Risky

Syntax and format
What it catches
Typos, missing @, invalid characters
Typical result
Invalid
Domain and MX records
What it catches
Domains that don't exist or don't accept mail
Typical result
Invalid
Mailbox (SMTP)
What it catches
Mailboxes that were deleted or never existed
Typical result
Invalid
Catch-all domain
What it catches
Servers that accept any address, so the mailbox can't be confirmed
Typical result
Risky
Disposable address
What it catches
Temporary inboxes that expire within hours or days
Typical result
Risky
Role account
What it catches
Shared addresses such as info@, support@, sales@
Typical result
Risky
Spam traps
What it catches
Known addresses used to catch senders with poor list hygiene
Typical result
Invalid
Complainers
What it catches
Addresses known for frequently marking mail as spam
Typical result
Risky

No verification service can find every spam trap. A lot of them are kept private by the people who run them. We remove the ones we know about and regular list hygiene takes care of the rest.

Valid, Invalid, Risky or Unknown: What Each Result Means

Warmy's email verification tool gives every address one of four results and each one has a next step. So cleaning a list isn't just guessing yes or no.

Valid

What it means

The mailbox exists and accepts mail

What to do

Send

Invalid

What it means

The address doesn't exist or can't receive mail

What to do

Remove from the list

Risky

What it means

The address might be deliverable but verification can't be as sure about it as with a valid one. Catch-all or role-based or disposable or long-inactive addresses

What to do

Exclude, or send in a small separate segment

Unknown

What it means

The receiving server didn't confirm, for example because of a timeout or greylisting

What to do

Re-verify later or exclude

Clean the List You Have, or Stop Bad Data at Signup

Use bulk email verification for email list cleaning on the contacts you already have. Use real-time checks to stop bad addresses from getting into your list at all. Most teams need both.

Bulk email verification

Upload a CSV or pull a list from your sending platform and Warmy verifies every address in one run. Use it before a campaign or after importing a lead list or before moving to a new ESP. You can also use it on a database you haven't emailed in a while. Then download the clean list or send it back to your platform.

Real-time verification at signup

Check each address when it's typed into a signup form or a checkout or a CRM import. Typos and fake addresses get caught while the person is still on the page and not after the first bounce.

Email Verification Is Only One Part of Deliverability

A clean list removes bounces you could avoid but it doesn't guarantee inbox placement. Authentication and sender reputation and sending volume and content and engagement all decide where your mail lands. Warmy is email verification software built into a deliverability platform so list quality connects with the rest. You verify the list and prepare the sending domain and test placement and then monitor.

Verification + warm-up

Start with clean contact data while Email Warm-Up builds your domain's reputation or keeps it where it is.

Verification + inbox placement

Send to a seed list and see if the campaign lands in Inbox or Promotions or Spam at Gmail and Outlook and Yahoo.

Verification + authentication checks

Check SPF and DKIM and DMARC and DNS setup in Deliverability Insights and DMARC Monitoring.

Verification + monitoring

Watch bounces next to blacklist status and reputation signals. Then bad data is just one signal in the health of your whole sending setup.

Your Contact Data Stays Yours

When you upload a contact list you're trusting a vendor with personal data. Warmy only uses your lists to give you verification results and never shares or resells them.

Encrypted in transit and at rest
Deleted on request
GDPR-ready, with a data processing agreement on request
Access limited to your workspace members and roles

Clean the List Before the Campaign Pays the Price

Used by cold email teams and agencies and e-commerce marketers and SaaS signup flows and high-volume senders.

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What Is an Email Verification Tool?

An email verification tool checks if an email address can receive mail before you send to it. It checks that the address is formatted right and the domain has working mail servers and the mailbox exists. Then it flags addresses that are risky to send to like disposable or role-based or catch-all addresses.

An email verification service does the same checks on whole lists before a campaign or an import and also through an API when someone signs up. That way invalid addresses get removed before they turn into hard bounces.

When to Verify Your Email List

Verify new contacts as they're collected. Also verify any list you import or enrich or get from a data provider or haven't emailed in a while. Do it before you send to it.

New signups and form leads: Verify in real time at signup
Lead list from a data provider or event: Verify the whole file before the first send
List you haven't emailed recently: Re-verify before the next campaign
Bounce rate rising on recent campaigns: Verify the full list and pause risky segments
Moving to a new ESP or a new sending domain: Verify before import, then warm up the domain

A lower hard-bounce rate is safer for sender reputation and verification removes clearly invalid addresses before they turn into bounces you could avoid. Lists also go stale on their own because people change jobs and abandon mailboxes. Microsoft lists regular removal of invalid addresses as a recommended practice for high-volume Outlook.com senders.

FAQ

Frequently Asked
Questions

What is email verification?

Email verification is basically checking if an email address is real and active and ok to send to. It looks at the format first and then confirms the domain and MX records exist and then it checks if the mailbox actually takes mail. All of this happens before your campaign goes out.