When should I stop retrying and suppress the address?

You've been retrying a soft bounce for days. At some point, you have to ask yourself: am I being persistent, or am I just adding noise to a server that clearly doesn't want your email? Knowing when to stop is one of those decisions that protects your sender reputation more than it might feel like it should.

The short answer is this. If an address has soft-bounced across three or more consecutive campaigns, it's time to suppress it. One bounce from a full mailbox? Fair enough. Three bounces in a row with no successful delivery in between? That mailbox is probably abandoned, overfull, or pointed at a domain that's no longer receiving mail.

Here's how to think about the two main signals.

Time-based. Your retry window should cap out around 48 to 72 hours for a single message. After that, the receiving server has had plenty of time to accept it. If it hasn't come through by then, keep the address on your list for now but note the bounce. It's not a death sentence after one attempt.

Pattern-based. This is where suppression decisions should really live. An address that soft-bounces on your October send, your November send, and your December send has shown you a pattern. There's no reason to believe January will be different. Suppress it.

There's also a harder signal worth watching. Sometimes a soft bounce escalates to a hard bounce by the end of your retry window. The server goes from saying "try later" to saying "this address doesn't exist." When that happens, suppress immediately and don't wait for a pattern.

A few quick rules of thumb that work well in practice:

• 1 soft bounce in 1 campaign: note it, retry normally, don't suppress yet
• 2 soft bounces across 2 campaigns: put the address on a watch list
• 3 soft bounces across 3 campaigns: suppress it
• Any hard bounce or 5xx permanent failure: suppress immediately, no waiting

And when you suppress, log why. "Suppressed after 3 consecutive soft bounces" is useful data. It lets you (or your team) review the record later if the contact shows up again through a new form submission or a support ticket. It also keeps your bounce history clean enough to audit if your deliverability dips and you need to figure out what happened.

Suppression isn't giving up on a contact forever. It's protecting your sending reputation while they're unreachable. If they come back through a double opt-in or verified signup, you can re-add them with a fresh history. But continuing to send into a bouncing address? That's the thing that actually hurts you.

Not sure if your ESP handles any of this automatically? The next question in this series covers exactly that. And if you want a second set of eyes on your list before things get messy, RME Clean can flag the addresses you should already have suppressed.