feat: adapt smtprelay role for external use

roles/smtprelay/templates/main.cf.j2

@@ -3,7 +3,7 @@ biff = no
 
 # appending .domain is the MUA's job.
 append_dot_mydomain = no
-myorigin = mateu.be
+myorigin = {{ smtprelay_origin }}
 
 # Uncomment the next line to generate "delayed mail" warnings
 #delay_warning_time = 4h
@@ -17,7 +17,7 @@ smtp_sasl_auth_enable = yes
 smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
 smtp_sasl_security_options = noanonymous
 smtp_use_tls = yes
-relayhost = [smtp.libertus.eu]:587
+relayhost = [{{ smtprelay_host }}]:{{ smtprelay_port }}
 
 ## only accepts local relay
 mynetworks = 127.0.0.0/8, 172.17.0.1/16