--On Sunday, March 30, 2008 4:10 PM +0200 Arnt Gulbrandsen
There is another argument: A fair amount of software
constructs email addresses, most notably
The best I can say for these addresses is that they're
syntactically valid. It would be a great joy to me if all the
muckware would stop assuming that blah(_at_)hostname is a
deliverable email address.
Of course, the firm requirement in 2821 that all domains in
email addresses be fully-qualified, plus either a little
knowledge or a quick determination that "hostname" is not a TLD,
is sufficient to reject such messages as non-deliverable as soon
as they touch the mail system and possibly earlier. The fact
that those rejections do not occur often enough may be more
evidence about the futility of trying to fix these sorts of
problems by fine-tuning standards.