opensmtpd service: fix evaluation error caused by Joachim's refactoring

Changed files
+1 -1
nixos
modules
services
+1 -1
nixos/modules/services/mail/opensmtpd.nix
···
chown smtpq.root /var/spool/smtpd/purge
chmod 700 /var/spool/smtpd/purge
'';
-
serviceConfig.ExecStart = "${opensmtpd}/sbin/smtpd -d -f ${conf} ${args}";
+
serviceConfig.ExecStart = "${pkgs.opensmtpd}/sbin/smtpd -d -f ${conf} ${args}";
environment.OPENSMTPD_PROC_PATH = "${procEnv}/libexec/opensmtpd";
};