Reading delivery failures properly.
HARD BOUNCES
The address does not exist, or the domain does not accept mail.
Permanent. Remove immediately. A reputable platform does this automatically; confirm yours does.
Repeatedly sending to hard-bouncing addresses is one of the clearest signals of a poorly maintained list.
SOFT BOUNCES
Temporary: a full mailbox, a server unavailable, a message too large.
Platforms retry automatically for a period.
Remove an address that soft bounces repeatedly over several campaigns; it is effectively dead.
BLOCKS
The receiving server refused the message on reputation or content grounds.
Different from a bounce. It means the address exists and your mail was rejected.
A rise in blocks is a deliverability problem, not a list problem.
WHAT THE BOUNCE MESSAGE SAYS
Platforms record the reason. Read it rather than treating all failures identically.
A pattern of blocks from one provider points at your standing with that provider.
ACCEPTABLE RATES
Very low on an established list. A rise after an import means the imported addresses were stale.
WHAT TO CHECK QUARTERLY
Bounce rate by type. Rising hard bounces means the list is ageing and needs pruning.
