feat: do not resolve MX records during configuration

MX record lookup was only used to detect Google Workspace domains.
They can still be configured manually.
We anyway do not want to encourage creating new profiles
with Google Workspace as we don't have Gmail OAUTH2 token anymore
and new users can more easily onboard with a chatmail relay.

src/configure.rs

@@ -300,8 +300,6 @@ async fn get_configured_param(
         param.smtp.password.clone()
     };
 
-    let proxy_enabled = ctx.get_config_bool(Config::ProxyEnabled).await?;
-
     let mut addr = param.addr.clone();
     if param.oauth2 {
         // the used oauth2 addr may differ, check this.
@@ -343,7 +341,7 @@ async fn get_configured_param(
             "checking internal provider-info for offline autoconfig"
         );
 
-        provider = provider::get_provider_info(ctx, &param_domain, proxy_enabled).await;
+        provider = provider::get_provider_info(&param_domain);
         if let Some(provider) = provider {
             if provider.server.is_empty() {
                 info!(ctx, "Offline autoconfig found, but no servers defined.");