What’s the ideal suppression timing (immediate vs delayed)?
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Timing is everything when it comes to suppression. Move too fast and you lose real subscribers who just had a bad server day. Move too slow and you keep hammering dead addresses, which mailbox providers notice and hold against you.
The good news is the rule is simple once you understand the underlying logic. The bounce type tells you how long to wait.
Hard bounces: suppress immediately. If an address doesn't exist, the domain is invalid, or the rejection is permanent, there's nothing to wait for. Every retry makes you look worse. Suppress it the moment it comes back as a hard bounce and move on. No threshold needed.
Soft bounces: give it a window. A full mailbox, a temporarily busy server, or a greylisting response can all clear up on their own. Suppressing after one soft bounce is too aggressive. You'd lose real, active subscribers who just had an off day. The standard approach is to track consecutive soft bounces over a rolling window and suppress after a threshold is hit.
A common and reasonable setup looks like this:
- 3 to 5 consecutive soft bounces within a 7 to 30 day window triggers suppression
- A single soft bounce resets if the next send goes through cleanly
- Bounce type still matters within soft bounces: a full mailbox gets more patience than a repeated server rejection
Most ESPs like Mailchimp, Klaviyo, and Postmark handle some of this automatically, but their defaults aren't always the right fit for your list. It's worth checking what thresholds they apply and whether they distinguish between hard and soft bounce types before trusting the system to decide for you.
And one thing to watch out for: soft bounce data that stays siloed in your ESP and never makes it back to your CRM. If your CRM and ESP aren't syncing suppression status, you might suppress an address in one place and keep emailing it from another. That's a reputation hit that's entirely avoidable.
If you're not sure your current setup handles this correctly, or you want a second set of eyes on your bounce data, our SOS hotline is free and we're happy to take a look.
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