Victor Sudakov wrote:

> I think you misunderstood me. For example exim does not include
> content scanners in its own code. However, using content scanners, SPF
> checking etc in exim does not involve running a bunch of ancillary
> processes, which is the case with sendmail.

How does Exim do it? With shared library plugins? Or does it fork/exec
a subprogram? If the latter, that's vastly *less* efficient than a milter.

> BTW what is your opinion on DNSBL lookups? Should a well designed MTA
> include them in its own code?

No. (And indeed, Sendmail does not directly include DNSBL lookups...
they are implemented in its configuration language.)

[...]

> However, I vaguely remember some firewall products which remove
> certain fields from outbound E-mail and even HTTP requests. Perhaps it
> makes sense under certain circumstances. And I cannot think of any
> good use of the private Received: headers to the outsider.

Received: headers are likely of very little use to the outside, but may
be very useful for insiders who are trying to diagnose mail loop problems.
Since Received: headers are not a security risk (in spite of some "firewall
products" opinions) and may be useful for diagnosing mail problems, you
might as well leave them in.

Regards,

David.