Why was my contact blocked?

Blocked means the address matched one of our filters, and sending to it would probably damage your deliverability. Thunk Mail screens every address you add, whether one at a time or through a CSV import.

What to do about it

• Check the import report first. Open your Audience page, use the dropdown menu, and click Import History. Download the report for your import to see exactly which contacts were blocked and why.
• Clean your source list. Remove blocked addresses so your next import runs clean.
• Check for typos. A misspelled domain can match a blocked pattern. Worth a second look before assuming the filter is wrong.
• Ask us. If the address is definitely correct and definitely a real person, get in touch and we'll investigate.

The rest of this page explains what each filter is looking for.

Global suppression list

A globally suppressed address has been permanently removed from all sending. An address lands there when:

• The recipient unsubscribed. They opted out through the unsubscribe link in an earlier email.
• A hard bounce occurred. The address doesn't exist, or the mailbox is permanently unavailable.
• A spam complaint was filed. Someone marked an earlier email as spam. Mailing them again is how domains end up blacklisted.
• Manual suppression. An account administrator added the address by hand.

Suppressed contacts can't be re-added. That's intentional: these addresses put your whole account's deliverability at risk, not just one campaign.

Blocked domains

Some email domains are blocked outright:

• Disposable and temporary domains. These addresses are short-lived and never belong to a real, engaged recipient.
• Known spam trap domains. Anti-spam organizations run these to catch senders with poor list hygiene.

Blocked patterns

Certain address shapes are blocked because they're unlikely to be a real person, or they carry compliance risk:

• Role-based addresses. info@, admin@, support@, sales@, noreply@ and similar are shared mailboxes rather than individuals. Marketing mail to them draws complaints at a much higher rate.
• Suspicious patterns. Addresses matching known shapes for invalid, auto-generated, or test accounts.

Why this matters

Gmail, Outlook and Yahoo watch sender behavior closely. Mailing invalid, unsubscribed, or spam-trap addresses tells them you don't maintain your list, and the consequences land on everything you send:

• Your email starts going to spam for every recipient, not just the bad addresses
• Your sending domain gets blacklisted
• Your Thunk Mail account can be suspended

These filters exist so your mail keeps reaching the people who actually want it.

Related: How bounces, unsubscribes, and complaints work covers what happens to addresses after a send rather than before one.