Reverts 45b6c347, which kept nothing of such a message and raised an aged-out
condition: that departed from an accepted decision on a lead's word alone. The
concern behind it (the record keeps the subject, with no age) is its own issue.
A record kept without its body still carried its subject, which names whose mail it was, with no age. The lead decided such a message is not kept at all: the notice is taken, the message counted, and the log and an aged-out condition say how many messages of the stream aged out undelivered. Unrestricted streams are unchanged.
DEAD_LETTERS kept a message given up on MAIL forever and showed it whole to any caller of dead-letters, outside the grant and past MAIL's week. Per ADR 0376 §3-§6: the kept copy carries a per-message time to live of what is left of its stream's age (a copy already past it is kept without its body), DEAD_LETTERS and EVENTS allow per-message TTL, the list and show give no body or own headers for it, delivering it again needs a minute left and the copy keeps the time left, and its max-deliveries condition clears saying how many aged out undelivered and from which stream.
jochen