What are bounces and how Mailbo handles them

A bounce is an email that couldn't be delivered. Handling bounces well is essential — ignoring them quietly destroys your ability to reach the inbox.

Hard vs soft bounces

• Hard bounce — a permanent failure: the address doesn't exist, the domain is invalid, or you're blocked. These addresses are dead.
• Soft bounce — a temporary failure: a full mailbox, a message too large, or a server that's momentarily down. These may succeed if retried.

What Mailbo does automatically

• Hard bounces are suppressed. Once an address hard-bounces, Mailbo stops sending to it. You don't have to do anything.
• Soft bounces are retried for a while; if they keep failing, they're treated like hard bounces.
• Bounced contacts are excluded from every future send, which is why your recipient count can be lower than your total contacts (a good thing).

Configure this under Settings → Bounce handling, and set where alerts go under Settings → Business profile → Admin Email Addresses.

Why this matters so much

Mailbox providers watch how you treat bad addresses. Repeatedly emailing addresses that hard-bounce signals a dirty, possibly purchased list — and they'll start sending all your mail to spam, even to good addresses. Letting Mailbo suppress hard bounces protects your whole list.

Complaints (the other thing to watch)

A complaint is when someone clicks "report spam". Keep your complaint rate under 0.3% (Gmail/Yahoo's threshold; aim for under 0.1%). The best ways to keep it low:

• Only email people who opted in.
• Make unsubscribing easy (Mailbo does this for you).
• Send relevant content to a segmented audience.

Next: Why emails go to spam · What happens when someone unsubscribes