John R Levine wrote:
True statement, but that means the senders of the other 5% are now left
in the dark as to what happened to their mail.
Is there a proposed solution to that?
Talking out of my hat here, it is my impression that spam is much more
likely to be sent to bogus addresses than legit mail is, so however the
spam fraction of your mailstream, the spam fraction of your bounces is
likely to be even higher.
On my tiny mail system, most but not quite all of the bounces can be
handled as rejections at SMTP time. The ones I can't are generally
deliveries to scripts where the script decides whether it can accept the
mail. When those say nope, can't deliver that, when is it worth
generating a bounce?
Yes - in the larger scheme of things - absolutely yes.
Much of that concern are removed when you move those Scripts to DATA
level processing. Tiny systems can more than well afford to do this
type of DATA filtering. There is no difference between DATA processing
or POST SMTP processing - the results are both theoretically and
empirically the same. So what we are really talking about here is
using software or techniques that provides that capability.