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.

deltachat-ffi/deltachat.h

@@ -5350,11 +5350,9 @@ dc_provider_t*  dc_provider_new_from_email            (const dc_context_t* conte
 
 
 /**
- * Create a provider struct for the given e-mail address by local and DNS lookup.
+ * Create a provider struct for the given e-mail address by local lookup.
  *
- * First lookup is done from the local database as of dc_provider_new_from_email().
- * If the first lookup fails, an additional DNS lookup is done,
- * trying to figure out the provider belonging to custom domains.
+ * DNS lookup is not used anymore and this function is deprecated.
  *
  * @memberof dc_provider_t
  * @param context The context object.
@@ -5362,6 +5360,7 @@ dc_provider_t*  dc_provider_new_from_email            (const dc_context_t* conte
  * @return A dc_provider_t struct which can be used with the dc_provider_get_*
  *     accessor functions. If no provider info is found, NULL will be
  *     returned.
+ * @deprecated 2025-10-17 use dc_provider_new_from_email() instead.
  */
 dc_provider_t*  dc_provider_new_from_email_with_dns    (const dc_context_t* context, const char* email);
 

deltachat-ffi/src/lib.rs

@@ -4661,13 +4661,9 @@ pub unsafe extern "C" fn dc_provider_new_from_email(
 
     let ctx = &*context;
 
-    match block_on(provider::get_provider_info_by_addr(
-        ctx,
-        addr.as_str(),
-        true,
-    ))
-    .log_err(ctx)
-    .unwrap_or_default()
+    match provider::get_provider_info_by_addr(addr.as_str())
+        .log_err(ctx)
+        .unwrap_or_default()
     {
         Some(provider) => provider,
         None => ptr::null_mut(),
@@ -4686,25 +4682,13 @@ pub unsafe extern "C" fn dc_provider_new_from_email_with_dns(
     let addr = to_string_lossy(addr);
 
     let ctx = &*context;
-    let proxy_enabled = block_on(ctx.get_config_bool(config::Config::ProxyEnabled))
-        .context("Can't get config")
-        .log_err(ctx);
 
-    match proxy_enabled {
-        Ok(proxy_enabled) => {
-            match block_on(provider::get_provider_info_by_addr(
-                ctx,
-                addr.as_str(),
-                proxy_enabled,
-            ))
-            .log_err(ctx)
-            .unwrap_or_default()
-            {
-                Some(provider) => provider,
-                None => ptr::null_mut(),
-            }
-        }
-        Err(_) => ptr::null_mut(),
+    match provider::get_provider_info_by_addr(addr.as_str())
+        .log_err(ctx)
+        .unwrap_or_default()
+    {
+        Some(provider) => provider,
+        None => ptr::null_mut(),
     }
 }