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Your suppression list is the set of addresses Hiveku will not send to. Hiveku adds hard bounces and spam complaints to it for you, and you can add your own or import the list of the email service you used before.
Hiveku adds an address automatically when an email to it hard-bounces or its owner marks your email as spam. You don’t need to do anything to keep the list healthy, but you can look at it, add to it, and take off addresses that may be taken off.

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The Suppression list page

Go to Settings > Email Service > Suppression list. It lists every address on your list, newest first, with:
  • Why it is there, in plain words: Bounced, Marked as spam, Could not be sent, Do Not Contact or added by your team, Unsubscribed, or Another reason. Under it, the note stored with the address, such as “Imported from Mailgun”.
  • First added: the date the address first went on the list. An address taken off and put back keeps that date.
  • Take off, on an address that may be taken off. Kept on for good on an address that can never be taken off, such as a hard bounce or a spam complaint. Do Not Contact on an address marked Do Not Contact on a contact in the CRM, with a link to that contact.
Find an address with the search box, or show one reason at a time. Everyone on your team can see the list. Adding, taking off and importing need Email Service: Manage: owners and admins, or a role given it.

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Add an address

Click Add address, enter the address, choose why (Added by your team or Unsubscribed), add a note if you like, and click Add to the list. An address already on the list is left as it is. An address you add can be taken off again later.

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Take an address off

Click Take off next to it and confirm. Email from your account can go to that address again: campaigns, sequences, invoices and app email. An unsubscribe the person made from your campaigns or sequences still holds. An address that can never be taken off, such as a hard bounce or a spam complaint, shows Kept on for good instead. An address marked Do Not Contact on a contact shows Do Not Contact instead. Click Allow contact again on the contact’s page under it, then Allow contact again on the contact. That lifts it everywhere at once: email, CRM sequences, and texts unless the person texted STOP.

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Import a list from another email service

Moving from Resend, Mailgun or another email service? Bring its suppression list over, so the people who bounced, complained or unsubscribed there are not emailed from Hiveku.
1

Export the list from your old service

Download its suppression list as a CSV file: bounces, spam complaints and unsubscribes. Some services export each list as its own file. Import each one.
2

Open the import

On Settings > Email Service > Suppression list, click Import CSV, and choose the service you are moving from. Its name goes in the note of each address, such as “Imported from Resend”.
3

Say what the rows are

Choose what to call the rows the file does not mark as bounced, spam or unsubscribed: Added by your team, Unsubscribed, Bounced or Marked as spam. A file with a column that says each row’s type, such as Resend’s origin, keeps each row’s own type.
4

Choose the file

The page finds the column of addresses (named email or address, or one address on each line) and says how many rows it read and which columns it uses.
5

Check the file

Click Check the file. Each row’s result is listed, and nothing changes yet: Will be added, Will be put back on the list (an address taken off before), Will be kept on for good (an address that may be taken off now, which the file calls a bounce or a spam complaint), Already on the list, or Skipped, with why: not one email address, or listed earlier in the file.
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Import

Click the Import button, which says how many addresses it will add or change. When some are bounces or spam complaints, Hiveku asks first: those stay on the list for good. Each row’s result is listed again, as it was done.
Bounces and spam complaints you import stay on the list for good: nobody can take them off later, on the page, through the API or through your AI assistant. Import only addresses your old service marked that way.
A file can hold up to 5,000 addresses and 5 MB. Split a longer list into several files. Save the file as CSV, with commas between columns. Importing the same file twice is safe: addresses already on the list are left as they are.

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Other ways to manage suppressions

Ask your AI assistant what you want:
Or:
It can list, add and remove suppressions. It refuses to remove a hard bounce or a spam complaint.

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Suppression types

Every entry has a type that says why it is there. The page shows it in words. Your AI assistant can also record other types. The page shows them as Another reason. Hiveku does not suppress soft bounces, such as a full mailbox or a passing DNS failure.

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Best practices

Wire your app’s unsubscribe handler to the suppression API. When someone unsubscribes, add their address. That is faster and safer than keeping a separate opt-out table.
  • Leave bounces alone. The mail server said the address does not exist. Hiveku keeps it suppressed for you.
  • Respect complaints. Someone who marked you as spam stays suppressed. Do not try to mail them from another account or domain.
  • Note why you remove an address. Keep your own record of who was taken off the list and why.
  • Bring your old list with you. When you move from another email service, import its suppression list before your app sends from Hiveku.
  • Don’t clean a list by sending to it. Check a cold list with a list validation service before you import it.
See Deliverability for more on list hygiene.

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Check a suppression

1

Add a test address

Suppress an address you control, on the Suppression list page, through your AI assistant, or through the API.
2

Send to it

Send an email to it and to one other address through the REST API. The answer lists the test address in suppressed_recipients, and the email goes to the other one only.
3

Send to it alone

With the test address as the only recipient, the REST API refuses the email with 400 all_recipients_suppressed, and nothing is sent.

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Troubleshooting

Check why on the Suppression list page. Bounced means the address does not exist on the recipient’s mail server: check for a typo or a different domain. Marked as spam means the person marked you as spam: do not send to them again. Neither can be taken off if it was recorded since 12 September 2026, or imported.
The address shows Kept on for good: a bounce or a spam complaint that cannot be taken off. Or it shows Do Not Contact: open the contact from the link under it and click Allow contact again. If you see no buttons at all, your role cannot change the list: an owner or admin can, or can give your role Email Service: Manage.
The key lacks the email:suppressions permission. Tick Manage Suppressions on the key’s page under Settings > API Keys, or add the address on the Suppression list page.
Each skipped row says why: not one email address (an empty cell, a name, or two addresses in one cell), or listed earlier in the file, where it is counted once. Fix the rows and import the file again: addresses already on the list are left as they are.
A fast-growing list is a warning sign. Check your opt-in flow (are people really agreeing?), look for a broken form that submits made-up addresses, and check cold lists before you import them.
Click Take off next to your address on the Suppression list page, or ask your AI assistant: “Remove my-email@example.com from my email suppressions. I added it by mistake.” Then send your test again.

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What’s next?

Email Webhooks

React as bounces and complaints happen

Deliverability Reference

Keep your sender reputation clean