Clean your Substack subscriber list
Export your Substack subscribers as a CSV, verify every address, then import the valid file back and keep the risky one out of your first send. Verification finds addresses that cannot receive mail. It cannot tell who has stopped reading, and an address it cannot confirm is called risky, never valid.
Export steps, bounce rules and prices read from Substack's own pages on 23 Oct 2026.
1. Export your Substack subscribers
- In your Substack dashboard, open the Subscribers page.
- Apply filters first if you only want part of the list.
- Use the export option above the subscriber list to export it as a CSV.
- Download the CSV once the export is ready.
Source: Substack help: export your email list. Or see the shorter Substack export page.
2. What Substack already does with bounces
- We could not find a Substack help article that states a bounce-rate limit or says how hard-bounced addresses are handled, so treat the platform as the one place you cannot see the line you are being measured against.
- Substack's own site says writers keep 90% of paid revenue minus card fees. There is no per-subscriber charge for a free newsletter, which means a dirty list costs you reach and reputation, not a bigger bill. (Substack: going paid)
Inactive is not invalid. A subscriber who has not opened for a year usually has a working mailbox, so verification keeps them. Deal with them separately: segment by last engagement, send a re-permission email, and remove the ones who do not answer. Verification is for the addresses that would bounce.
3. What verification can and cannot tell you
It can tell you
- The address is malformed or the domain has no mail servers.
- The mailbox does not exist, where the provider answers the check.
- The domain is disposable, which is common for junk signups.
- The domain accepts all mail, so the address cannot be confirmed.
It cannot tell you
- Whether the person reads your issues.
- Whether they agreed to hear from you.
- Whether the address is a spam trap.
- Whether a risky address is real. Providers that hide mailbox status and catch-all domains stay unconfirmed.
Unconfirmed always means risky, never valid. You get three files back, valid, risky and invalid, with your original Substack columns kept.
4. Import the clean file back
- Import the valid file as your active list. Keep the original columns so tags, names and signup dates survive.
- Do not re-import the invalid file. Addresses the platform already suppressed stay suppressed, and re-adding dead ones only brings the bounces back.
- Hold the risky file out of the first send. Mail it later, to the most engaged people first, and watch the bounce rate on that send.
- Substack only wants people who agreed to hear from you. Verification removes dead addresses, it does not make a list without permission acceptable.
Substack bounce rate limits
Substack does not publish a bounce-rate threshold that we could find. Source: Substack help centre, read 23 Oct 2026. Other platforms' published lines are in bounce rate limits by platform.
How much is a dirty Substack list costing you?
Enter your own numbers. The share of dead addresses is your estimate (your last bounce rate is a floor, since only some dead addresses have bounced yet). Nothing is sent anywhere.
Invalid or abandoned, your best estimate.
Fill in the list size and the share of dead addresses to see the result.
Substack takes a share of paid subscription revenue and does not price by subscriber count, so the calculator shows deliverability effects only. Substack: going paid, read 23 Oct 2026. Prices change; check the page before you decide.
Check a Substack address, then your list
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
By continuing you agree to our Terms and Privacy Policy.
Common questions
- How do I export my Substack subscribers?
- In your Substack dashboard, open the Subscribers page. Apply filters first if you only want part of the list. Use the export option above the subscriber list to export it as a CSV. Download the CSV once the export is ready.
- What bounce rate does Substack allow?
- Substack does not publish a bounce-rate threshold that we could find. Source: Substack help centre, read 23 Oct 2026.
- Will verification find the inactive subscribers on my Substack list?
- No. Verification tells you whether an address can receive mail, not whether the person reads it. Someone who has not opened in a year can have a perfectly valid mailbox. Handle disengaged people with an engagement segment and a re-permission or sunset email, and use verification for addresses that are invalid or at risk of bouncing.
- What does a risky result mean?
- A risky address could not be confirmed as a real mailbox, usually because the domain accepts all mail (catch-all) or the provider will not say. An unconfirmed address is never reported as valid. Keep risky addresses out of your first send and mail them later, most engaged first.
- Is there a free way to try this on my Substack list?
- Yes. Sign in with Google and the first 100 addresses are checked free, with results to download and no card. After that, verification is $29.99 a month on the Pro plan.