To the inbox and beyond

Verify up to 10,000 emails in one batch

Review email risk signals before outreach and help protect your sender reputation.

Import. Verify. Outreach.

Use verification statuses to review data quality before contacts enter your workflows. Credit usage follows the rules shown in the product.

Seamless Import: Drag and drop your prospect lists directly into Overloop.‍
Automatic Validation: Overloop flags invalid emails immediately upon import.
‍Safety filters: Verified leads are immediately available for your campaigns.‍

Launch in just 5 minutes

Multi-step checks before outreach

Overloop combines syntax, domain, SMTP, and catch-all signals. Verification can reduce risk, but it does not guarantee delivery or inbox placement.

Syntax & Domain Health

We instantly reject typos and domains that are inactive or miss-configured (MX records), keeping your list hygienic from the start.

SMTP Handshake

Overloop queries the recipient server for available mailbox signals without sending an email. An SMTP response is not proof of future delivery.

Catch-All Detection

We identify servers that accept all incoming mail (Catch-All). In Overloop, these are marked as "uncertain", allowing you to decide whether to take the risk or play it safe.

Automate verification via API

Keep your CRM clean programmatically. When you create a prospect via the Overloop API, we automatically verify their email status, returning distinct values for valid, invalid, or uncertain.

Start Automating

Usecases

Why verification matters for your pipeline

Verify my list

Review risky addresses before sending

High bounce rates can affect sender reputation. Overloop flags invalid and uncertain addresses so your team can decide which contacts to suppress.

Optimise your spend, focus on real buyers

Use status filters to review addresses marked invalid or uncertain before sending. Campaign results still depend on targeting, copy, and sending conditions.

Built on expertise. Trusted by industry leaders

We poured a decade of outbound knowledge into a platform that fuels high-performing sales teams

Clean your lists.
Close more deals.

Safeguard your sender reputation and start your next campaign with confidence.

Start verifying today

Explore more than
130 reviews

Discover us on G2

What is email verification?

Email verification evaluates syntax, domain, SMTP, and catch-all signals before you send. Overloop checks addresses in real time or in bulk and flags invalid, catch-all, and risky results. These are risk signals, not delivery or inbox-placement guarantees; you can review up to 10,000 emails in one batch.

How email verification works in Overloop

Syntax check
Every address is checked for formatting errors and typos that would bounce instantly.
Domain and MX check
Overloop checks whether the domain resolves and advertises a configuration for receiving mail.
Mailbox ping
An SMTP check queries available signals for the mailbox without sending an email; the result does not guarantee later delivery.
Catch-all and risk scoring
Catch-all domains and high-risk addresses are flagged so you decide how aggressive to be.
Straight into your campaign
Verification statuses can feed sequence rules; configure how invalid and uncertain contacts are handled.

Why teams choose Overloop for email verification

Protect your sender reputation

Cleaning your list can reduce bounce risk. Inbox placement also depends on the domain, content, sending pattern, and recipient system.

Verify in bulk, fast

Check up to 10,000 addresses in one run and review the returned statuses instead of verifying a list row by row.

Built into your outreach

Overloop can check contacts as they enter a campaign so your team can review their status before outreach.

A decade of deliverability

Overloop comes from the team behind Prospect.io and brings experience with factors that influence email delivery.

When to verify your email list

Verification isn't a one-time chore, it's a habit that protects every campaign you send. Verify at these moments in particular:

Before every cold email campaign. Lists decay fast, people change jobs and inboxes close. Re-verify right before you send, not weeks earlier.
After buying or scraping a list. Purchased data is the riskiest of all. Never send to it un-verified, one bad batch can tank your domain.
Before re-engaging old contacts. A list you haven't touched in months is full of dead addresses. Clean it before you reach back out.
On your signup forms. Catch typos and fake addresses at the point of entry so bad data never gets into your B2B contact database.

The addresses Overloop catches before you send

Not every bad address bounces the same way, and some quietly hurt you more than others. Verification flags each type so you send with confidence:

Invalid addresses. Mistyped or non-existent mailboxes that bounce instantly and signal carelessness to inbox providers.
Catch-all domains. Domains that accept anything, so delivery is unconfirmed. Overloop flags them so you weigh the risk.
Role-based addresses. Generic inboxes like info@ or sales@ that rarely convert and often trigger filters.
Disposable and spam-trap risks. Throwaway domains and known trap patterns that can get your domain blacklisted if you hit them.

Who it's for

Cold emailers protecting a sending domain, SDR and marketing teams importing bought or scraped lists, and agencies running email for multiple clients, anyone who can't afford a high bounce rate to quietly wreck their deliverability.

Frequently asked questions

What does email verification actually do?

Email verification evaluates syntax, domain, SMTP, and catch-all signals to classify an address as valid, invalid, uncertain, or risky. These signals are not proof that a mailbox is real or that a future message will be delivered.

How accurate is Overloop's verification?

Overloop combines syntax, domain, mailbox, and risk signals, and flags catch-all or risky addresses. Results are probabilistic and may change as recipient systems respond.

Can I verify a whole list at once?

Yes. You can verify up to 10,000 emails in a single bulk run, and verification also happens automatically as contacts enter a campaign.

Will verification reduce my bounce rate?

Removing addresses marked invalid or risky before sending may reduce bounce risk. It cannot prevent every bounce, and sender reputation depends on additional factors.

What is a catch-all address?

A catch-all domain accepts mail to any address, so it can't be confirmed as a real mailbox. Overloop flags these separately so you decide whether the risk is worth it.

Is it GDPR-compliant?

Overloop publishes privacy, security, and data-processing documentation. Each controller's GDPR compliance depends on its lawful basis, data sources, configuration, and use; this is not legal advice.

How is verification different from a warm-up tool?

Verification cleans the list you're about to send to. Warm-up builds your domain's reputation over time. You need both, and clean data comes first.

Does verifying hurt my sending reputation?

Overloop's mailbox checks do not send a message to the recipient. SMTP queries still interact with recipient infrastructure, and their result is not proof of a real mailbox or future delivery.

Do I pay for verifying invalid addresses?

You verify your list once and keep the clean result, so the cost of a quick verification pass is trivial next to a single ruined sending domain or a campaign that lands in spam because of a high bounce rate.

Can I verify contacts one by one and in bulk?

Both. Overloop verifies single addresses in real time as you work and runs bulk checks of up to 10,000 at once, so it fits list-building and one-off lookups alike.

Your next big customer is waiting...

Access a 450M+ B2B contact database with built-in email verification.

Start searching today