failure verifiedcritical
Permanently failed mail
Messages that have finally failed, with the full history of attempts that led there.
In detail
More valuable than the success queue for deliverability work: it carries the state and outcome of every attempt, the codes the receivers returned and their own wording. That is the raw material for bounce classification. Worth remembering what does not arrive here: a message still being retried. Intermediate attempts exist only in the send log, so a node with a large deferred backlog can have an almost empty failure queue and still be in trouble.
What happens if you get it wrong
Left empty because the routing key was cleared.Failures are reported nowhere; there is no second copy to fall back on.inference · inference