chore: sync mailcore v0.1.0-beta.1

mailcore/examples/test_dns.rs

@@ -0,0 +1,18 @@
+use mailcore::dns::discover_mail_server;
+
+#[tokio::main]
+async fn main() {
+    let email = std::env::args().nth(1).expect("Usage: test_dns <email>");
+
+    println!("Discovering server for: {}", email);
+
+    match discover_mail_server(&email).await {
+        Ok(config) => {
+            println!("✓ IMAP: {}:{}", config.imap_host, config.imap_port);
+            println!("✓ SMTP: {}:{}", config.smtp_host, config.smtp_port);
+        }
+        Err(e) => {
+            eprintln!("✗ Error: {}", e);
+        }
+    }
+}