Retry-Time is actually 4:30 instead of 5 Minutes.

[bennet-esyoil]

Describe the bug

E-Mails that bounced without the server answering a retry-time will be requeued after 4:30 instead of 5 Minutes, because there is a query here, that returns retry_after - 30 seconds.

Ref.: https://github.com/postalserver/postal/blob/main/app/models/queued_message.rb#L39

To Reproduce

Send an E-Mail that bounces, let it requeue and look at the timestamps in the deliveries table.

Expected behaviour

Requeues should only happen after 5 minutes have passed.