Suppression list
A suppression list is the set of email addresses a sender must never email again, kept in one place so that no campaign and no tool can reach them by accident.
Also called Email suppression list, Do-not-contact list, Unsubscribe list.
A suppression list is the set of addresses you have promised never to email again. It sits in front of every send, and the check is simple: if the address is on the list, the message does not go, whatever campaign it belongs to and whoever wrote it.
It exists because the law in most places requires an opt-out to be honoured for good, and because mailbox providers notice when people who asked to be left alone hear from you anyway. A complaint from one of them costs the sending domain more than the message could have earned. It is also the decent thing to do. Somebody said stop.
What goes on it
Four kinds of address belong there. People who unsubscribed, by clicking the link or by replying with words to that effect. Addresses that hard bounced, because a mailbox that does not exist will not exist next month either. Anyone who marked a message as spam. And anyone who told you, in any channel, to stop writing. Once an address is on the list it stays there; a suppression list only grows.
Suppressed is different from not interested
The mistake that causes real trouble is treating every no as the same event. A reply that says "we already use something" or "not right now" is a no to one pitch from one product. That conversation should close and that person should not hear about that product again, and nothing more follows from it. A reply that says "take me off your list" is consent withdrawn. It applies to the person, whatever you might sell them from now on, and it belongs on the suppression list.
The list also has to be one list. A company that runs three products with three outreach tools and keeps three unsubscribe lists has not honoured anything: the person who opted out of product A gets product B's sequence a month later, from the same company, and is right to complain. An address is suppressed for the whole sender, across every product and every person sending on its behalf, or it is not really suppressed.
How Kamu applies it
When a reply asks to be taken off the list, or someone clicks the unsubscribe link, Kamu writes the address to a suppression list shared across every product in the account, and it checks that list before any send, before the address is even verified. A reply that says not interested closes that one conversation and touches nothing else: the person is not written to again about that product, and is not suppressed for the others.
In practice
- A founder who replied "unsubscribe" to an email about product A, and never hears about product B from the same company either.
- An address that hard bounced in March and is still refused in September, even after a freshly imported list contains it again.
- Not on it: a prospect who replied "we already have a tool for this", whose thread closes without the address being suppressed.
Questions
What is the difference between a suppression list and an unsubscribe list?
An unsubscribe list holds the people who clicked the link. A suppression list is broader: unsubscribes plus hard bounces, spam complaints and anyone who asked in words to be left alone. Tools use the two terms loosely, and the useful question to ask of any of them is whether the list is checked before every send from every product, or only inside the campaign it was built in.
Does a suppression list expire?
No. A hard bounce could in theory be a mailbox that comes back, and a person who unsubscribed could change their mind, and the sender does not get to decide either of those. If someone wants to hear from you again they can write to you, and that new consent is theirs to give. Treat the list as permanent and only growing.
Is a suppression list required by law?
The mechanism is not named in most laws; the outcome is. CAN-SPAM requires an opt-out to be honoured within ten business days and never sold or transferred. GDPR and PECR require that an objection to direct marketing is respected without conditions. A shared, permanent suppression list is the only practical way to meet those requirements once more than one person or tool is sending. None of this is legal advice.
Should I suppress people who said not interested?
Not automatically. A no to one pitch is information about that pitch, and the person has not withdrawn consent to hear from you. Close the conversation, record the reason, and do not write to them about the same thing again. If they say stop, or ask to be removed, that is the moment the address goes on the suppression list.
Related terms
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