Re: reliability principles

> I suppose that, after sending a private message to the wrong place,
> you'd say ``Just ask him not to read it''?

If a user makes a mistake and misdirects a message to an incorrect mailbox,
and it has left the local spool, what else *can* you do ?

> However, you have to reduce the probability of a failure to reasonable
> levels.

Sure -- as I read maj's message, it's a matter of choosing what "reasonable"
is ...

> If you don't deal with OS crashes, you will have terrible
> failure rates---more than one failure per 10^9 messages.

OK -- so you appear to have a different expectation ...
If we have one message failure in the next 500 years I would not consider
that a "terrible failure rate" !

> That's why the consensus of the community is that losing a message to an
> OS crash is (to quote RFC 1123) ``frivolous.'' Every mailer is required
> to deal with OS crashes; you MUST NOT accept a message by SMTP if you
> are not going to take your responsibility seriously.

Are you suggesting that exim does not "deal" with OS crashes ?
If so, on what is this based ?

> As another example, if your ``OS gremlin''---sorry to hear about that---
> were a common problem on, say, SGIs, people who wanted to run mailers on
> SGIs would have to take measures to reduce the probability of a gremlin
> eating mail.

Sure -- I thought that was maj's basic point.
If there's a problem, you "appropriate" steps to improve things.
I understood him to be indicating that it's the weakest link which has to
be fixed.

>> My view is that you should do the best you conveniently can,
> That's not good enough when you're transporting people's mail. If you
> don't spend the time to achieve the reliability levels required by
> RFC 1123, your mailer doesn't belong on the Internet.

This is sounding like flame wars.

You appear to be slagging off exim without pointing out the problems,
and telling people how to run their systems.
I don't know you from Adam, but I have known the author of exim and maj
for some years (I suspect 18 or so !) so I may be somewhat prejudiced and
behind the times, but you don't seem to be convincing me ...


To get things in perspective, where does exim fit in in your view of MTAs ?
Apart from qmail, which MTAs are "acceptable" ?
Where do sendmail, smail, zmail, MMDF, PP, etc fit in ?