Updated development build restores the TLS_PROTOCOL setting, with the
remaining available options, and updating the verifyfilter module to cache
validated E-mail addresses.
- OpenSSL 1.1.0 update. Some options to select specific TLS protocol levels
are no longer available. The TLS_PROTOCOL setting adjusted accordingly, and
the deprecated options are mapped to their nearest approximate setting. No
changes to the GnuTLS alternative option.
- maildrop: added the new "system" command.
- The SMTP sending code has been rewritten and factored out into an internal
- New "verifyfilter" module, a filter module that verifies the email sender
address by initiating a callback connection to the sender's domain, using
the internal SMTP library. The module is also available as a "verifysmtp"
command-line tool, that does the same.