Bounces, Complaints and Suppressions
Why some contacts stop receiving email, and why that protects you.
What It Is
A suppression is a block on one email address. While an address is suppressed, nothing you send will go to it — not a sequence, not a broadcast, not a one-off message.
Suppressions are created automatically when something goes wrong with a delivery, or deliberately when someone opts out. You can see all of them under Opt-outs & Suppressions at the bottom of Communication > Email > Analytics & Reputation.
Why It Matters
A suppression looks like a lost contact. It is closer to a seatbelt.
Repeatedly mailing an address that does not exist, or one whose owner reported you, is exactly the behaviour inbox providers use to identify senders worth blocking. Suppressing the address protects the delivery of everything else you send.
It is also a consent record. Someone who opted out or complained has told you something, and the list is where that is remembered — which is why reactivating an address is a deliberate act with a confirmation step, not a toggle.
How It Works
Three reasons. Hard bounce means the address does not exist. Spam complaint means a recipient reported your message. Manual means it was added on purpose, by you or on a contact's request.
Three origins, shown alongside the reason. Recipient is the person themselves, through an unsubscribe or a complaint. Customer is your own organisation. Admin is a platform-level action.
Suppressions belong to a message stream, and you usually send on more than one — a transactional stream and a broadcast stream. One opt-out normally results in the address being suppressed on all of them, so the list shows one row per address with every affected stream tagged on it. Where streams disagree, the row shows the most serious reason.
Your CRM follows the list. When the page loads, any contact whose primary or secondary address appears in the suppression list is marked as opted out of email, so future sends skip them. The page says when it has changed anything. The sync only ever adds an opt-out — it never clears one, so it cannot undo a choice you have made in the CRM.
Examples
A contact leaves their company
Their work address stops existing, so the next send hard bounces and the address is suppressed. It appears with reason Hard bounce and origin Recipient, and the matching CRM contact is marked as opted out. If you learn their new address, add it to the contact — the suppression applies to the old address, not the person.
Someone reports a nurture email as spam
The address is suppressed with reason Spam complaint. This one is permanent: it cannot be removed from the list by you or by Zyntro, and the row shows Locked instead of a Reactivate button. If they want your email again they have to ask for it through a fresh signup.
A contact asks to be taken off everything
Adding them as a manual suppression stops all email immediately and records why. Reason shows as Manual, and because it was a request rather than a complaint it can be reversed later if they come back.
The same address appears suppressed on two streams
It is shown as a single row with two stream badges. Reactivating from that row lifts the suppression on every stream at once, so you do not have to repeat the work per stream.
Warning: Spam complaints cannot be undone. Hard bounces and manual suppressions can be lifted if the contact has given consent again — see Reactivate a Suppressed Contact.
