Dear guix,

Exim has no authenticator drivers. By default, they don't get included
in the binary, but in my case, I want to set up an internet site with
authenticated SMTP 
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-smtp_authentication.htm
. Authentication is necessary, otherwise the system is vulnerable to
spam abuse.

The fix would be to un-comment the following lines in the src/EDITME
(copied as Local/Makefile):

# AUTH_CRAM_MD5=yes
# AUTH_CYRUS_SASL=yes
# AUTH_DOVECOT=yes
# AUTH_EXTERNAL=yes
# AUTH_GSASL=yes
# AUTH_HEIMDAL_GSSAPI=yes
# AUTH_PLAINTEXT=yes
# AUTH_SPA=yes
# AUTH_TLS=yes

Unfortunately, CYRUS_SASL requires cyrus-sasl as a native input and
GSASL, gsasl. HEIMDAL_GSSAPI does not seem to build.

However, it is vital to have plaintext (it is the only one used in the
default exim configuration, 
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_default_configuration_file.html
) and it would be nice to have the other as authenticators. What do you
think?

Best regards,

divoplade