Use the opensmtpd package as it was updated in guix

Julien LepillerThu Feb 20 16:45:42+0100 2020

20e2957

system-configuration/modules/services
namelast commitdate
mail.scmUpdate dkimproxy-out service to use guix packages and guile config wrapperWed Jul 31 09:49:23+0200 2019