Mailbase
Start free
DeliverabilityUpdated · 7 min read

Email Bounce Management for SaaS Teams

Hard vs soft bounces explained, what causes them, how to handle each, acceptable bounce rates, and why suppressing bounces automatically protects your sender reputation.

MT
Mailbase Team
email bounce management
On this page · 8 sections

Overview

A bounce is an email the receiving server rejected. Managing bounces matters because mailbox providers read a high bounce rate as a spam signal — sending to dead addresses doesn't just waste effort, it lowers inbox placement for your good recipients too. The core discipline is simple: tell hard from soft bounces, stop sending to hard bounces immediately, and keep your overall rate low by verifying before you send.

Hard vs soft bounces

A hard bounce is permanent — the address doesn't exist, the domain is invalid, or the server permanently rejects you. Hard bounces must be suppressed immediately and never emailed again; repeatedly hitting them is one of the strongest negative signals there is. A soft bounce is temporary — a full mailbox, a message too large, or a server briefly unavailable. Providers retry soft bounces automatically, but an address that soft-bounces repeatedly over time should be treated as dead and suppressed.

Watch for the gray cases too: some "bounces" are actually blocks (the receiver rejecting you on reputation grounds) — those signal a deliverability problem, not a bad address, and mean you should fix authentication or reputation rather than just removing the contact.

  • Hard bounce = permanent (bad/nonexistent address) → suppress now
  • Soft bounce = temporary (full mailbox, server busy) → auto-retried
  • Repeated soft bounces → treat as dead, suppress
  • Block-style bounces signal a reputation problem, not a bad address

How to handle bounces and keep the rate low

Automate it: feed every hard bounce straight into your suppression list so it can never be re-sent, and a good platform does this for you — Mailbase enforces suppression at send time across bounced, complained, and unsubscribed contacts. The upstream win is prevention: verify addresses before sending and use confirmed opt-in so dead and fake addresses never enter the list.

Keep your bounce rate under about 2% (lower is better) — Google's sender guidelines effectively demand it. If bounces spike on a previously clean list, suspect a deliverability/reputation issue (blocks) rather than assuming every address went bad overnight.

  • Auto-suppress hard bounces; never re-send to them
  • Prevent bounces with verification and confirmed opt-in
  • Keep bounce rate under ~2%
  • A bounce spike on a clean list = reputation issue, investigate

Common mistakes

  • Skipping SPF, DKIM, and DMARC, or assuming they're a one-time setup.
  • Sending real volume from a brand-new, un-warmed domain.
  • Reusing a stale list without re-verifying, so bounces spike.
  • Ignoring complaint rate until a single bad campaign sinks the domain.

Sources and further reading

Official docs for current setup details, pricing, and API behavior — verify specifics there, since they change.

Amazon SES docsSupabase custom SMTP docs

Related guides

More on email bounce management and the surrounding deliverability workflow:

free domain checkSPF, DKIM, and DMARCdeliverability and honest warm-upsuppression listsunsubscribe best practicessender domain docsunsubscribe and compliance docs
Questions

About this page.

What's the difference between a hard and soft bounce?
A hard bounce is permanent — the address doesn't exist or is invalid — and must be suppressed immediately. A soft bounce is temporary, like a full mailbox or a busy server, and is retried automatically. An address that soft-bounces repeatedly should be treated as dead and suppressed.
What is a good email bounce rate?
Under about 2%, and lower is better. Google's sender guidelines effectively require keeping invalid sends minimal, so verify addresses before sending and auto-suppress hard bounces. A rate climbing above that risks spam filtering for your whole list.
How do I reduce email bounces?
Verify addresses before sending, use confirmed (double) opt-in so fake and mistyped addresses never enter the list, automatically suppress every hard bounce, and re-verify cold segments before reusing them. Prevention upstream matters more than cleanup after.
Why did my bounce rate suddenly spike?
On a previously clean list, a sudden spike often means a deliverability or reputation problem — the receiver is blocking you, not that addresses went bad. Check your authentication (SPF/DKIM/DMARC) and reputation rather than just removing the bounced contacts.