Suppression

Suppression lists stop your email reaching addresses you must never mail: people who asked you to stop, addresses that belong to a competitor, domains you don't want to send to. A suppressed contact stays in your lists, marked Suppressed, and is left out of every campaign and trigger email.

The three suppression lists

Go to Lists → Suppression and choose a list:

List	What it blocks	Typical uses
Email Suppression	Individual email addresses	People who complained or asked to stop, legal requests, addresses you know are invalid
Domain Suppression	Every address at a domain	Competitors, disposable email services, domains with high complaint rates
IP Suppression	Contacts who engage from an IP address, range or subnet	Bot traffic and security scanners that open and click your email

Global or one list

Every entry has a scope:

Scope	What it covers
Global	Every list in your account, including lists you create later
A single list	Only that list. The Associated List column shows which.

Use Global for anyone who must get nothing from you at all, such as people who complained or made a legal request. Use a single list when someone should only stop receiving one kind of email, and remember that they can still be mailed from your other lists.

Unsubscribes apply to one list

When a contact unsubscribes, Mumara ONE marks them Unsubscribed on the list the email was sent to, and they can still be mailed from your other lists. To stop all email to them, add them to Email Suppression with Global selected.

How suppression takes effect

• Existing and future contacts. An email or domain entry matches contacts you already have and contacts you add later, whether by import, web form, the API or by hand.
• Regular synchronisation. The suppression list is synchronised with your contacts at regular intervals. A note above the table says how often: "Suppression list synchronizes every … minutes." New entries take effect within that time.
• Suppressed, not deleted. Matching contacts stay in their lists and show Suppressed. Remove the entry and they're released again at the next synchronisation.

Email Suppression

Go to Lists → Suppression → Email Suppression.

Column	What it shows
ID	The entry's number
Email	The suppressed address
Reference	The note entered when the address was suppressed
Associated List	Global, or the list the entry applies to. Click a list's name to see only its entries.
User	Who added the entry
Created On	When it was added
Actions	Delete the entry, or delete every entry with the same reference

Suppress email addresses

1. Click Add New. The Suppress Email Addresses window opens.
2. Under Select List, choose Global or a single list.
3. Under Email Hashing, keep No Hashing for ordinary addresses. If your account offers MD5, choose it when your file holds MD5 hashes of the addresses instead, as some suppression lists shared between companies do.
4. Under Source, choose how to provide the addresses:
   • Upload a CSV file: choose a file with one address per line. The maximum file size is shown next to the field. Set Includes header? to Yes if the first row is a column name.
   • Input email addresses: type or paste the addresses, one per line.
5. Enter a Reference, such as complaint via support or legal request 2026-09. It's required, and it lets you find or remove these entries together later.
6. Click Import.

A file upload runs in the background and shows its progress: the total records, how many were suppressed, and how many were duplicates or invalid. Cancel import stops it. Addresses already processed stay suppressed.

Export

Choose Bulk Actions → Export all to export your email suppression list. When it's ready, download it under Tools → Exported Files. See Exported Files.

Domain Suppression

Go to Lists → Suppression → Domain Suppression.

Column	What it shows
Domain	The suppressed domain
Reference	The note entered when it was suppressed
Associated List	Global, or the list the entry applies to
Created On	When it was added
Actions	Edit, Delete and Flush reference

Suppress domains

1. Click Add New. The Suppress Domains window opens.

2. Under Select List, choose Global or a single list.

3. Under Source, choose Upload a CSV file with one domain per line, or Input domains and type them in, one per line.

4. Enter domains without @ or www, for example:

   example.com
   example.net

5. Enter a Reference and click Import.

Every address at a suppressed domain is blocked: suppressing example.com covers alice@example.com, bob@example.com and so on. It covers that exact domain only, so suppressing example.com doesn't cover mail.example.com.

Use Edit to change an entry's domain, list or reference, and Bulk Actions → Export all to export the list.

Your plan can limit how many domains you can suppress. If you reach the limit, you'll see how many you can still add.

IP Suppression

Go to Lists → Suppression → IP Suppression.

IP suppression works differently from the other two. It doesn't look at addresses: when a contact opens your email or clicks a link, the IP address they did it from is compared with your IP suppression list, and if it matches, the contact is suppressed so no further email is sent to them.

That makes it useful against automated traffic, such as security scanners and bots that open and click every link in the email they process, and whose activity would otherwise distort your statistics.

Only contacts who engage are checked

A contact is only checked against IP suppression when they open or click. Contacts who never engage are never matched.

Column	What it shows
IP Address	The IP address, range or subnet
Associated List	Global, or the list the entry applies to
Reference	The note entered when it was added
Created On	When it was added
Actions	Edit, Delete and Flush reference

Suppress IP addresses

1. Click Add New.

2. Under IP Address, enter one entry per line, in any of these forms:

   Form	Example	Covers
   Single IP	203.0.113.10	One address
   Range	203.0.113.0-20	A range in the last part of the address: here 203.0.113.0 to 203.0.113.20
   Subnet (CIDR)	203.0.113.0/28	A whole subnet

3. Under Contact List, choose Global or a single list.

4. Enter a Reference and click Submit.

Invalid or duplicate entries are reported and skipped.

Remove suppression entries

• One entry: click its delete icon, or choose Delete from its Actions menu, and confirm.
• Several entries: tick them and choose Bulk Actions → Delete.
• Everything with one reference: use the reference icon on Email Suppression, or Flush reference on Domain and IP Suppression. Every entry with that reference is removed after you confirm.

Released contacts are no longer Suppressed after the next synchronisation. They can be mailed again, unless they've bounced, complained or unsubscribed.

Only release people you may mail

Before removing an entry, make sure you have permission to email that person again. Mailing people who complained or asked you to stop leads to more complaints, and can breach anti-spam law. See Compliance.

Bounces, complaints and unsubscribes

You don't need suppression lists to handle bounces and complaints: Mumara ONE processes them for you and updates the contact.

Event	What happens to the contact
Hard bounce	Marked Hard Bounced and left out of your campaigns
Soft bounce	Marked Soft Bounced. Still mailed.
Spam complaint	Marked as spam (Spammed) and never mailed from that list again
Unsubscribe	Marked Unsubscribed on that list

These statuses apply to one contact on one list. To stop all email to an address across every list, suppress it globally. See Bounces and Complaints for how bounces and complaints are processed.

A contact can also show as Suppressed because of an entry Mumara's team added for your account, for example after a recipient reported your email to Mumara's abuse team and asked not to be mailed again.

See who's suppressed

• On Contacts → View/Search Contacts, set the status filter to Suppressed.
• When you view one list's contacts, add the Suppressed column with Prioritize Columns. See Contacts.
• In a segment, filter on Suppression status. See Segments.

Good practice

• Suppress complaints and stop requests globally, straight away.
• Use clear references, so you can find, explain or remove a batch later.
• Keep suppression entries when you delete contacts. An entry also blocks the address if it's imported again.
• Review from time to time. Rapid growth in suppressions usually points to a list-quality problem worth fixing at the source.

Troubleshooting

Problem	What to check
A suppressed address still received email	The entry was added after the email was sent, or before the next synchronisation. Check that it's Global, or tied to the right list, and that the address is spelled exactly as in your list.
Many rows came back invalid	Check the file has one entry per line, and that the Source and Includes header? settings match it.
An IP entry never suppresses anyone	IP suppression only applies to contacts who open or click from that address. Check the entry's format.
A contact is still suppressed after you removed the entry	Wait for the next synchronisation. The contact may also match another entry, such as a domain entry or a global one.

Next steps

• Bounces and Complaints: how Mumara ONE handles bounces, complaints and unsubscribes
• Contacts: view and manage contacts
• Segments: target, or exclude, groups of contacts