On Fri, 26 Mar 2004, John C Klensin wrote:
(3) A comment in the "timeouts" section that it may be
appropriate to establish a shorter expiration on the
requeue and retry period for an NDN than for normal
message traffic. E.g., if a particular system is
configured to retry normal outgoing messages for up to
four days, it might sensibly be configured to give on
trying to transmit bounce messages after only one or two.
I would welcome this change.
As a worked example I will point out that I have been doing this since
some time last year. I have a separate queue set aside for the delivery
of NDNs. The timeout for maximum time in queue is extremely short: 4
hours.
I justify the short timeout because everything on my server is done
immediately. So, if I'm sending you an NDN then you must have sent me
the original message within the last 5 minutes. Although there's
certainly a window of vulnerability my view is if you just sent me a
message and you're not ready to hear about its status, then you lose.
And even with a 4 hour timeout the steady state for the number of queue
entries is just short of 1,000 messages. I could reduce that if I had
more aggressive spam filters but that's an entirely separate issue.
Four hours may be too short as a recommendation in the standard.
For completeness, this is separate from virus scanning.
Jim