Use Case

Validate on Import. Not After the Damage Is Done.

Every contact list import is a risk. Purchased lists, event signups, partner data shares, CRM migrations — bad emails sneak in through all of them. Validate at the point of entry and keep your database clean from day one.

upload CSV and file uploads.: Upload a list and get results back with every email tagged as valid, invalid, or risky. Download clean and dirty lists separately.
api API-driven ingestion.: Validate emails programmatically as they flow into your system — webhooks, form submissions, third-party syncs.
sync Integration syncs.: Connect your CRM or ESP directly. Truelist validates contacts as they sync, so bad data never makes it into your marketing platform.

Bulk Email Verification

Verifying List

marketing-contacts.csv

0 of 5

Email	Status
sarah.jones@acme.co	Checking...
mike.chen@techcorp.io	Pending
lisa.wang@startup.com	Pending
invalid@test	Pending
john@catchall.net	Pending

0 Ok

0 Risky

0 Invalid

The cost of cleaning up later

Most teams import first, clean later. By then, the damage is already done.

mail Bounced campaigns: You import a list, send a campaign, and 15% bounces. Your sender reputation takes an immediate hit that affects every future send.
analytics Polluted segments: Invalid contacts dilute your segments and skew reporting. Open rates, click rates, and conversion metrics all look worse than they actually are.
payments Wasted ESP costs: Most ESPs charge by contact count. Every invalid email in your database is money spent storing and attempting to email someone who doesn't exist.
warning Spam trap contamination: Purchased or scraped lists often contain spam traps. A single spam trap hit can get your domain blocklisted. Validating on import catches these before they cause damage.

Where bad data sneaks in

CSV uploads: Exported lists from events, conferences, webinars, and partner data shares. Often months old with high decay rates.
CRM migrations: Moving from one CRM or ESP to another? Years of accumulated bad data migrates too unless you validate during the transition.
Third-party syncs: Lead enrichment tools, form builders, landing page platforms — any external data source can introduce invalid addresses into your system.

Three ways to validate on import

Choose the method that fits your workflow.

upload

Upload a file

Drag and drop a CSV into Truelist. Get back a clean list with every email tagged. Download valid, invalid, and risky lists separately.

api

Use the API

Validate emails programmatically with the batch or inline API. Perfect for automated pipelines that ingest contacts from multiple sources.

sync

Connect your platform

Direct integrations with Mailchimp, HubSpot, Klaviyo, and more. Validate contacts as they sync — no code required.

Clean data starts at import

Upload your first list for free. No credit card required.

Start verifying for free View pricing

Frequently Asked Questions

Can't find the answer you're looking for? Reach out to our support team.

What file formats can I upload?: Truelist accepts CSV and TXT files. The email column is auto-detected, or you can specify it manually. Additional columns (name, company, etc.) are preserved in the output.
How long does bulk validation take?: Speed depends on list size and validation strategy. A 10,000-email list typically completes in 5-15 minutes. You'll get an email when results are ready.
Can I validate via API during a CRM migration?: Yes. Use the batch API to validate large lists, or the inline API to validate one-by-one as records are migrated. Both approaches work well for migrations.
What results do I get back?: Every email is tagged with a status (valid, invalid, risky, unknown) and a detailed sub-status explaining why (e.g., "mailbox not found", "disposable domain", "accept-all server"). You can download filtered CSVs for each category.
How does pricing work?: Truelist offers flat monthly pricing — validate as many emails as you need without per-email charges. Your first 1,000 emails are free.