Gary Feldman <gaf(_at_)ziplink(_dot_)net>
I'm not sure I buy that reasoning. You seem to be saying that since it's
not possible to detect all invalid addresses syntactically that the ability
to trap some syntactically (or more than currently trapped) is irrelevant.
Well, assume for the sake of argument that it's relevant. Is it also
valuable enough to justify changing email after 25 years of production
use, with a user base presumably in the hundreds of millions, using god
knows how many thousands of different programs?
I personally think this particular syntax wart should've been killed at
birth... but now it's too late.
I disagree. I believe it's usually faster, simpler, and more reliable to
catch errors syntactically than relying on subsequent semantics.
Usually?
Each extra syntax check involves writing at least one more test in the
code, at least two more test cases to verify the code's correctness, some
documentation and some (UI and documentation) translations. And then
there's the (slightly) increased cost of learning the code for the
subsequent maintainers, and the UI for the users.
Add it up¹ and multiply it by the number of MUAs/MTAs in use. What you get
is the cost of retrofitting this check now.
--Arnt
1: Believe in the goodness of your fellow man. Pretend that a significant
portion of those MUAs/MTAs have test cases and documentation. ;)