Re: TINW was RFC2821b is-01 Issue 1: trailing dot in Domain

My two cents:

It's better to disallow localpart(_at_)tld as email address in 2821bis. That 
is, I prefer to remain compatible with 2821 rather than with 821.
I have two arguments:

1. The change in 2821 hasn't caused a signficant level of problems, 
AFAICT, so why change again?
2. I see quite a few addresses of the form 'localpart(_at_)hostname'. Say 
between 1% and 1ppm of messages. If 'localpart(_at_)tld' is guaranteed not 
to be valid, a smarthost's life is simpler: 'localpart(_at_)something' is 
either a local address (not subject to IETF rules) or invalid. A 
smarthost has to decide whether it's valid by local rules or not, 
that's all. There is no possibility that the address might have two 
valid meanings.
Arnt