Hard Bounce vs. Soft Bounce
A hard bounce means the address is dead for good; a soft bounce means it failed temporarily.
What it means
A hard bounce is a permanent failure — the address doesn't exist, the domain is gone, or the recipient's server has permanently refused delivery. A soft bounce is temporary — a full inbox, a server briefly down, or a message that was just too large — and a later attempt might succeed.
Why it matters
Providers watch your hard-bounce rate closely and will start throttling or blocking your sends if it climbs too high, so hanging on to addresses that keep hard-bouncing actively hurts delivery for everyone else on your list. Soft bounces are lower stakes on their own, but an address that soft-bounces repeatedly is usually heading toward being dead too.
ask datanephew
Should I remove someone after one bounce?
For a hard bounce, yes — datanephew can flag those so you know who to clean out. For a soft bounce, it is normal to leave them and see if it clears up over a few sends.
Is my bounce rate high enough to worry about?
Ask datanephew for your bounce rate trend over recent campaigns — a rate that is climbing, or sitting well above what's typical for your list size, is worth cleaning up before it affects deliverability.