Instantly vs Smartlead List Hygiene: A Side-by-Side Checklist
For list hygiene in Instantly, you can tag leads, delete invalid ones from a single campaign or lead list, and block addresses workspace-wide, but you cannot pause a single lead through the API. In Smartlead, you can tag, pause (reversible), delete and block globally, but only on campaigns, and the API limit is much lower. The checklist below works on both: verify the leads in place, tag first, look at the counts, then remove or pause. On Smartlead, do it a day before launch.
The two platforms side by side
| Instantly | Smartlead | |
|---|---|---|
| Sources you can verify in place | Campaigns and lead lists | Campaigns only (no lead lists in the API) |
| Tag with sv_status | Every checked lead | Risky and invalid leads (valid left as is to save calls) |
| Pause one invalid lead | Not possible through the API | Yes, in this campaign, and resumable |
| Delete invalid leads | From the chosen campaign or list only | From the campaign; a lead in no other campaign is also deleted from the account |
| Block list | Workspace-wide | Global, every campaign |
| API limit | 100 calls a second, 6,000 a minute per workspace | 60 a minute, 1,000 an hour per key (standard) |
| Write-back speed on a large campaign | Minutes | Can take hours |
These behaviours come from each platform's API docs and are listed with every endpoint on our Instantly and Smartlead integration pages.
The checklist
Before you import
- Remove duplicates and obvious role addresses you do not want (info@, sales@).
- Drop guessed name variants on the same domain: when three or more spellings of one name were checked on a domain that answers mailbox checks, only 1.6% existed in our catch-all study.
- On Instantly, import into a lead list first so you can check before anything enters a sequence.
Before launch
- Connect the platform on Integrations and run Verify leads on the campaign or list.
- Keep the default write-back (tag only) for the first run.
- Read the counts in Recent runs. If invalid leads are a large share, fix the source, not just the campaign.
- Smartlead: tick Pause invalid leads and re-run, or pause by hand on
sv_status. Allow for the hourly API limit. - Instantly: delete invalid leads from the campaign or list, and add them to the block list if you never want any campaign to reach them.
- Move risky leads to a separate, slower campaign.
Sending risky leads
- Send 100 to 300 risky leads from a warmed secondary inbox.
- Compare the bounce rate with the main campaign. Stop if it is high.
- Use catch-all likelihood grades to choose which risky leads go first: see catch-all emails: what to do.
After launch
- Turn on daily auto-verify for the campaign so new leads are checked as they are added (paid plans).
- Check your sending domains' SPF, DKIM and DMARC: see monitoring your sending domains.
Run 100 free checks on one Instantly or Smartlead campaign and work through the list above with real numbers.
Platform-specific reading
Common questions
What is the difference between Instantly and Smartlead for list hygiene?
Instantly supports lead lists as well as campaigns and has much higher API limits, but its API cannot pause a single lead. Smartlead can pause a lead in one campaign, which is reversible, but works on campaigns only and has a lower API limit, so writing back to a big campaign takes hours.
Should I delete or pause invalid leads?
On Smartlead, pause first: it stops their emails in that campaign and can be undone. On Instantly, where pausing a single lead is not possible through the API, tag them, then delete them from the campaign or list once you have checked the counts.
Does deleting a lead remove it from other campaigns?
On Instantly, deleting from the chosen campaign or list does not touch other campaigns. On Smartlead, its docs say a lead that is in no other campaign is also deleted from your Smartlead account.
What should I do with risky leads in Instantly or Smartlead?
Move them to a separate, slower campaign and send a small test batch from a warmed inbox. If that batch bounces well under your limit, send the rest the same way; if not, drop them.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.