When trying to use mail in a financial services environment, more and more, email needs to be fully auditable to be compliant.
Therefore, also a sender must be able to produce detailed evidence after the fact that mail submissions have been executed with due care.

Therefore, I suggest to add a new "mail.smtp.report" attribute that reports on at least the level "basic" and "advanced" what it did:

• E.g. "basic" could report in a single line

- certificate domain, key size, expiration, issuing CA, as well as the stream cipher employed (e.g.: was it only 40 bit?)

• "advanced" would also provide the certificates used in full, and possibly the session key (for later recovery of an archived transmission cryped stream in case DHE), size of transmission, etc.

A first step would be to simply print that "accountability info" to stdout/stderr, later the javamail API hopefully eventually will provide an extended transport.send() interface to return such audit related objects.

Related are https://bugzilla.mozilla.org/show_bug.cgi?id=227096
and https://bugzilla.mozilla.org/show_bug.cgi?id=227097