Re: namedroppers, continued

> > - nomadic users have valid reasons to post from random places on the net
> >   (including multiple ISPs) and keep the same mail from address.
> then, i'm sorry that i'm such a poor writer.  i tried to cover this case:
>
>    3.3. Roaming hosts such as laptop computers will probably not be able to
>    be listed in the MAIL-FROM MX RR for their return address domain name,
>    and may be forced to use an intermediary for outbound e-mail.  STARTTLS
>    or an SSL/SSH tunnel back "home" may become a necessary first hop for
>    mobile e-mail.
>
> > - many ISPs won't let you forward or submit mail through someone else's
> >   SMTP server, even if you have permission to do so.  so you can't
> >   forward your mail through your "home" ISP's mail server to allow the
> >   "mail from" check to work.
> in that case you'd be wise to not insert a MAIL-FROM MX for your domain.
what this seems to require is to have different sets of domains for 
use in MAIL FROM addresses - those for which source verification can
be expected and those for which it cannot.  there are some current
domains which are naturally and exclusively in the former category - 
say hotmail.com; but most domains are probably not exclusively in 
either category.  so it would require establishment of new domains and 
reconfiguration of systems to use those domains to be effective - along 
with the educational effort that this entails.  and it would still
leave a significant portion of mail without a way to identify its source.

Keith