What is a bounce and what should you do with it?

A bounce is a returned message. There are two kinds, and treating them the same damages your reputation.

The hard bounce

The address does not exist or no longer exists. Remove it immediately and permanently. Continuing to send to these is the most damaging signal there is.

The soft bounce

Mailbox full, server temporarily unavailable. Retrying makes sense, but not indefinitely. After several consecutive failures, treat the address as hard.

Why it matters

A high bounce rate tells mail providers you are sending to a list you do not maintain. That affects delivery of all your messages, not just the bouncing ones.

Automate it

Manual bounce handling does not get done. Connect the feedback to your list so removals happen automatically.

Look at the reason

Many bounces from one domain are not dead addresses but a block. That is a different problem and needs a different response.