Verify the leads in your Instantly campaigns

Why check a campaign, not just a list

Leads sit in a campaign for weeks while people change jobs and companies change domains. An address that was fine when you imported it can bounce by the time the third follow-up goes out. Checking the campaign itself, right before a send or once a week, catches those addresses without exporting and re-importing a file.

How it works

1. Subscribe to Pro or Email + Phone, then open Campaign integrations in your dashboard.
2. In Instantly, go to Settings > Integrations, open API Keys and click Create API Key.
3. Give it the campaigns:read and leads:read scopes. For write-back, add leads:delete and block_list_entries:create, or use all:all. Instantly shows the key once, so copy it.
4. Paste the key and click Connect. We check it with Instantly before saving it.
5. Choose a campaign from the list. It is read live from your account.
6. Leave write-back off to only check the leads, or turn it on and pick what should happen to invalid leads.
7. Read the confirmation, which lists exactly what will happen, and start the run.
8. Open History to follow progress and download the results.

What we read and what we change

Only documented Instantly API endpoints are used. To check a campaign, SimpleVerifier reads:

• GET /api/v2/campaigns lists your campaigns so you can pick one. docs
• POST /api/v2/leads/list pages through the chosen campaign's leads, 100 at a time. docs

With write-back turned on for a run, and only once its verification has completed, it calls these for leads marked invalid. Nothing is written when write-back is off, when the run is canceled, or when you remove the key first.

• DELETE /api/v2/leads deletes the invalid leads from that campaign, by lead ID, in batches of 100. docs
• POST /api/v2/block-lists-entries/bulk-create adds the invalid addresses to your workspace block list. docs

• Removal is scoped to the campaign you picked: the request names that campaign and the exact lead IDs, so leads in your other campaigns are not deleted.
• Instantly's block list applies to the whole workspace, so a blocked address is not emailed from any campaign.
• Instantly's API limits are shared across the workspace (100 requests a second, 6,000 a minute). A run stays well under them.

What the results mean

• Valid: the mail server confirmed the mailbox exists.
• Risky: it may work, but delivery isn't confirmed, for example a catch-all domain. Write-back never touches these; decide for yourself.
• Invalid: it will bounce, or it's a disposable address. These are the only leads write-back acts on.

The results file keeps each lead's email, name, company and Instantly lead ID, so you can match rows back to the campaign.

Common questions

How do I verify the leads in a Instantly campaign?

Connect your Instantly API key in the SimpleVerifier dashboard, pick the campaign and start a run. SimpleVerifier reads the campaign's lead emails through the Instantly API and checks each one with the mail server. Results appear in History as valid, risky or invalid with a reason, with the same downloads as an uploaded CSV.

Does SimpleVerifier change anything in my Instantly account?

Not unless you turn on write-back for that run. With it off, SimpleVerifier only reads campaigns and leads. With it on, and only after verification has completed, it acts on leads marked invalid: it can delete these leads from the campaign and/or add these addresses to your Instantly workspace block list. Risky leads, such as catch-all domains, are never touched.

How is my API key stored?

It is checked with Instantly, encrypted with AES-256-GCM using a server-side key, and stored on our server. It is never shown again or sent back to your browser, and it is not written to logs. Removing the key in the dashboard deletes it, and any pending write-back is then skipped.

How many leads can one run check?

Up to 100,000 leads per run, the same limit as a CSV upload. Very large campaigns can take more than a day to finish, because mailbox checks run within a daily capacity; History shows how far a list has got.

Which plans include it?

Pro ($29.99/month) and Email + Phone ($49.99/month), with no per-lead charges. Pay-as-you-go credit packs do not include integrations; you can still export a CSV from Instantly and upload it.

Which Instantly API version does it use?

API v2, with your key sent as a Bearer token. Keys from the older API v1 will not work; create a v2 key under Settings > Integrations > API Keys.

Why was my Instantly key rejected?

A 401 from Instantly means the key is wrong or was revoked; create a new one. A 403 usually means the key is missing a scope: it needs campaigns:read and leads:read, plus leads:delete and block_list_entries:create for write-back. A 402 means the Instantly workspace has no active paid plan, so its API is off.