Substack Import Held for Review or Denied? What to Do

The problem

"My client had his ability to import csv files with subscribers restricted. It says we need to contact TOS to have the restriction lifted." (r/Substack, September 2026)

"Tentando pela milésima vez importar meus contatos no Substack, que não tá aceitando por nada no universo." ("Trying for the thousandth time to import my contacts into Substack, and it just won't accept them.") (@eusouomatt on X, October 2026)

Getting people onto a Substack list came up in 23 of the 111 forum and review sources we coded in our review of public Reddit, X and forum posts (October 2026). Four of those were about consent and import blocks. A writer in a Meta ads thread said "I got blocked when I added even 10 emails of my friends", and a B2B marketer with a CRM list ran into Substack's guidelines before importing at all (r/marketing).

The frustration is real: the review notice tells you little, and a denial gives no line-by-line reason. But the rules behind it are written down. This guide sets them out, as of October 2026, and shows how to prepare an import that passes.

Why does Substack hold imports for review?

Substack screens every list. Its import policy explains why: "Spam complaints can damage deliverability for our entire creator community and prevent publishers from reaching their audiences."

1. Automated risk checks run on upload. "Substack has a number of detection mechanisms in place to assess how risky your import list might be."
2. Risky lists go to people. If those checks suggest "your email list contains recipients who have not explicitly opted in to receiving messages from you", your publication and list "may be flagged for review by our Standards & Enforcement team".
3. The review target is 72 hours. The team "works hard to ensure your list is reviewed within 72 hours", with occasional delays at high volume (review help).
4. Big lists get verified anyway. Even a clean list, if "really big", will be "asked to undergo a verification review" (size limits).

A hold is not an accusation. It means the automated checks couldn't confirm consent on their own.

Which lists get denied?

The policy and the Content Guidelines are explicit about what fails:

List type	Likely outcome	Rule
People who subscribed to your newsletter elsewhere (Mailchimp, Kit, Ghost, beehiiv)	Passes, possibly after review	"lists contain only those who have explicitly opted in to receiving messages from your publication"
Mixed list: some subscribers, some "engaged" followers	Likely denied; can lead to restrictions	The agency in the restricted-import thread imported "a mix of people who had explicitly opted in and others who were engaged with our content on other platforms"
CRM contacts, customers, webinar or giveaway leads	Likely denied	"Collections of contacts, leads, or other sources where all participants did not opt in are likely to be denied"
Your address book or social followers	Prohibited	"don't import your contacts list or social graphs" (Content Guidelines)
Purchased or scraped emails	Prohibited	"We don't allow imports of email addresses that were purchased, scraped, or harvested from third party websites" (Content Guidelines)
People who unsubscribed from you before	Skipped	Substack shows "No valid emails found. This could be because an email previously unsubscribed" (help)

The denial article is short: Substack "may deny email lists we believe are high risk". It doesn't promise a reason for each list.

How do I prepare an import that passes?

Follow Substack's import guide, with these preparation steps first:

1. Filter to opted-in people only. Export from your old tool with "subscribed" status only. Drop unsubscribed, bounced, cleaned and "transactional only" contacts.
2. Use one column of emails. Substack recommends "only one column of emails in your email import list since names will not be imported" (size help).
3. Remove obvious junk. Duplicates and typo domains such as gnail.com are skipped anyway; role addresses (info@, sales@) rarely opted in.
4. Re-confirm stale lists first. For a list you haven't emailed in a long time, Substack suggests you "send your recipients an email asking them to explicitly opt in to receive emails through Substack" (import policy).
5. Upload and answer every optional question. Substack may ask where readers opted in, "including a URL". It says "Voluntarily answering all of these questions will increase the likelihood that your list is approved."
6. Keep your evidence. Save the signup-form URL, the consent wording and a dated export from the old tool. If the review team asks, you can answer in one reply.
7. Check legal basis for EU readers. Substack says it is "ultimately the responsibility of a Publisher to ensure that they have a lawful basis" to import a list (GDPR help).

After import, watch engagement. Substack may later ask you to prune imported readers who "have yet to read or engage with any of your content", and it says it "will never ask you to remove paying subscribers or those who have signed up to your publication manually using our subscription flow" (prune help).

What do I do if my import was denied or restricted?

1. Don't retry the same file. Re-uploading or splitting it looks like an attempt to get round review.
2. Switch to self-signup. Substack's own advice: "embed a manual signup form off-platform so we're certain your subscribers have opted in" (denial help). See embedding Substack on your website.
3. Email the list from your old tool with a link to your Substack /subscribe page and ask people to join. Everyone who clicks has opted in.
4. If imports were restricted, contact the TOS team. In the September 2026 thread, the reply that thread settled on was to say plainly what was imported, that the addresses not opted in would be removed, and that it wouldn't happen again (r/Substack).
5. Re-import only the clean part once you have a list where every person opted in to your publication, with the opt-in URL ready.

The wider picture of getting people in is in how to add subscribers to Substack.

What not to do

• Don't use bots, browser scripts or "add subscriber" robots to type a denied list in one by one. It sidesteps the review that protects your sender reputation and conflicts with Substack's terms.
• Don't import CRM, customer, event or giveaway lists unless the signup clearly said people were joining your newsletter.
• Don't buy, scrape or rent emails. The Content Guidelines prohibit importing them.
• Don't re-add people who unsubscribed. They have to subscribe again themselves.

Is there a tool that helps?

Our signup embeds send readers through Substack's own subscribe flow and keep a record of your consent wording and opt-in URL, and our import converter filters a list down to subscribed, de-duplicated emails before you upload. Neither can approve an import or get round Substack's review.