Fixes renewing email LE SSL certs. Do not abort when SSL is enabled for mail domains

bin/v-add-letsencrypt-domain

@@ -86,7 +86,6 @@ else
     is_system_enabled "$MAIL_SYSTEM" 'MAIL_SYSTEM'
     is_object_valid 'mail' 'DOMAIN' "$domain"
     is_object_unsuspended 'mail' 'DOMAIN' "$domain"
-    is_object_value_empty 'mail' 'DOMAIN' "$domain" '$SSL'
 fi