Re: Re: RFC: Making mail-transport-agent Priority: optional

[Josh Triplett <josh@joshtriplett.org>]

Steve Langasek wrote:
> On Sat, Oct 15, 2011 at 06:53:02PM +0100, Ben Hutchings wrote:
> > > Hear, hear.  "How do I deliver mail?" is a per-system setting, not a
> > > per-application setting,
> 
> > It's not per-system, or even per-user.
> 
> > If I want to send mail from my personal address I should send it through
> > my own smarthost.  If I want to send mail from my work address I *must*
> > send it through the work smarthost (thanks to SPF).  I could possibly
> > configure this at the MTA level, but no other user should be allowed to
> > use my credentials to send mail through the work smarthost.
> 
> Needing to send mail through specific per-user smarthosts is the exception,
> not the rule.  Most machines have a designated forwarding smarthost based on
> who their ISP is, not based on which email address someone wants to use.

Every ISP mailserver I've seen, and for that matter almost every other
mailserver I've seen, requires SMTP AUTH to send mail; the SMTP AUTH
credentials vary by user.  And for that matter, while most of those
mailservers[1] will allow sending from email addresses other than the
one used for SMTP AUTH, many such servers *will* prohibit sending from
another address at the same domain/service, requiring you to SMTP AUTH
for that address instead.

- Josh Triplett

[1] Notable exception: gmail, which will silently change the from
    address to the primary address on the account, unless the user has
    proven they own the email address they want to send from.  Not a
    crazy policy for a mail server where anyone can trivially obtain an
    account for free, and thus banning someone for spamming just lets
    them create another account.