Verify the leads in your Smartlead 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. Sign in (free accounts work) and open Integrations in your dashboard.
2. In Smartlead, open your profile menu, then Settings > API Key Management. Under Admin API Keys press + Create API Key, name it, press Create, and copy the key straight away: Smartlead shows the full key only once.
3. Paste the key and click Connect. We check it with Smartlead before saving it.
4. Choose a campaign from the list. It is read live from your account.
5. Keep the default, tagging each lead with its result, or untick it to only check. Removal-type actions are off until you tick them.
6. Read the confirmation, which lists exactly what will happen and what it costs on your plan, and start the run. Optionally turn on daily auto-verify for new leads.
7. Open History to follow progress and download the results.

What we read and what we change

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

• GET /api/v1/campaigns/ lists your campaigns so you can pick one. docs
• GET /api/v1/campaigns/{id}/leads pages through the chosen campaign's leads, 100 at a time. docs

Only for the actions you choose on a run, and only once its verification has completed, it calls these: tagging writes each checked lead's result; removal, pausing and blocking act on leads marked invalid. Nothing is written when you untick everything, when the run is canceled, or when you remove the key first.

• POST /api/v1/campaigns/{id}/leads/{lead_id} tagging: writes sv_status and sv_verified_at into a risky or invalid lead's custom fields, keeping its existing fields; one call per lead. docs
• POST /api/v1/campaigns/{id}/leads/{lead_id}/pause pauses each invalid lead in that campaign, if you choose it. docs
• DELETE /api/v1/campaigns/{id}/leads/{lead_id} removes each invalid lead from that campaign, one call per lead. docs
• POST /api/v1/leads/add-domain-block-list adds the invalid addresses to your global block list. docs

• Smartlead's docs say that when a removed lead is not in any other campaign, it is also deleted from your Smartlead account. Leads that are in other campaigns stay there.
• Smartlead limits API calls per key (60 a minute and 1,000 an hour on its standard tier), so SimpleVerifier paces background calls to stay under the hourly limit. Reading takes one call per 100 leads; tagging, pausing and removal take one call per lead, so a large campaign can take hours to write back. That is why valid leads are not tagged.
• Smartlead's API has no lead lists and no account or workspace name, so the dashboard shows campaigns only and labels the connection by its key.
• Not yet tested against a live Smartlead account: the calls follow Smartlead's published API reference, and a wrong key is rejected by Smartlead's real API as expected. If something behaves differently in your account, write to [email protected].
• Subsequences are left out of the campaign list, because their leads come from the parent campaign.

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. Tagging marks them risky; they are never removed, paused or blocked.
• Invalid: it will bounce, or it's a disposable address. These are the only leads removal, pausing and blocking act on.

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

Common questions

How do I verify the leads in a Smartlead campaign?

Connect your Smartlead API key in the SimpleVerifier dashboard, pick the campaign and start a run. SimpleVerifier reads the campaign's lead emails through the Smartlead 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 Smartlead account?

Only what you choose for that run, and only after verification has completed. The default is tagging: writes sv_status and sv_verified_at into the lead's custom fields. Valid leads are left as they are, to save API calls. Nothing is removed or paused. You can also pause invalid leads in this campaign, or delete invalid leads from this campaign, or add invalid addresses to your Smartlead global block list; those act on invalid leads only, never risky ones, and need an explicit confirmation before the run starts. Only a confirmed mailbox is written as valid; anything unconfirmed is written as risky.

How is my API key stored?

It is checked with Smartlead, 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, turns off any daily auto-verify, and skips any pending write-back.

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.

What does it cost?

The same as uploading the leads as a CSV, one check per distinct address. A free account uses its free checks: if the campaign holds more leads than you have checks left, the first ones are checked and the rest stay unchecked. Starter uses the monthly allowance, Pro, Business and Agency their monthly full-speed volume and then the slow lane at no extra cost. The confirmation shows the numbers before anything starts.

Can it check new leads automatically?

Yes, on a paid plan. Turn on daily auto-verify for a campaign: once a day SimpleVerifier pulls the leads and checks only addresses it has not seen in that source before, up to 10,000 a day, with the write-back you chose. By default the leads already there are only remembered, not checked, so nothing is spent until new leads arrive. Free checks and pack credits are never used by the schedule.

Why was my Smartlead key rejected?

A 401 from Smartlead ("Invalid API Key") means the key is wrong or has been regenerated. Create a new key under your profile menu, Settings > API Key Management, Admin API Keys (Smartlead shows a key only once, at creation), then reconnect.

Does it work with Smartlead client (agency) accounts?

It reads the campaigns your API key can see. Blocked addresses are added to your global block list; no client ID is set.