Scripsit George Danchev <[EMAIL PROTECTED]> > IMHO a MTA must be capable acts as a client and as a server to transfer > messages between machines and is responsible for properly routing > messages to their destination, e.g. RFC 974. msmtp does not do all > of these, therefor it is not a MTA, and might have nothing to do > with /usr/sbin/sendmail.
You are wrong. See nullmailer. The definition of mail-transport-agent is that it provides a /usr/sbin/sendmail that local software can use to submit emails for delivery to arbitrary addresses with some reasonable expectation that it will actually be delivered. It is *not* required that the package that provides mail-transport-agent must itself do any particular part of the delivery process, as long as its /usr/sbin/sendmail will *somehow* arrange for delivery. It would be perfectly good to have a package airgap-mailer whose /usr/sbin/sendmail will just *print* hardcopies of its input on a configured printer, with instructions to the human operator to type the email into the machine at the Internet-connected side of the air gap. This package would provide mail-transport-agent because it implements the policy-defined API for shipping email for delivery. > Note that telnet does know nothing about smtp protocol. Neither does airgap-mailer. > > Note that a MTA isn't required to know ANYTHING about smtp. Suppose a > > package provides an sendmail that is an alias for 'ssh mailhub > > /usr/sbin/sendmail', then that package is a MTA. > Such a package will require a dependency of ssh (at least) on the remote > machine and you will be in a little trouble hacking your control file to > satisfy things like that ;-) That is up to the system administrator to arrange. If it provides a /usr/sbin/sendmail, then it is an MTA. It does not make it any less an MTA that it requires some manual configuration before its /usr/sbin/sendmail can do anything useful with its input. Most MTA's do, actually. > I think ssmtp is incorretly described as a MTA That must be because you don't understand what an MTA is. > WARNING: the above is all it does; it does not receive mail, expand aliases > or manage a queue. That belongs on a mail hub with a system administrator. Neither of these are necessary tasks for an MTA. -- Henning Makholm "The spirits will have to knit like banshees, but with enough spirits it *can* be done!"