Fix issues

lib/controllers/mail_client_controller.dart

@@ -1,5 +1,6 @@
 import "dart:io";
 import "package:enough_mail/enough_mail.dart";
+import "package:markdown/markdown.dart";
 import "package:nexusbot/controllers/settings_controller.dart";
 import "package:riverpod/riverpod.dart";
 
@@ -20,6 +21,25 @@ class MailClientController extends AsyncNotifier<MailClient> {
     return client;
   }
 
+  Future<void> sendMessage({
+    required String plainText,
+    required String markdown,
+    required String subject,
+    required MailAddress from,
+    required MailAddress to,
+  }) async {
+    final client = await future;
+    return await client.sendMessageBuilder(
+      MessageBuilder.prepareMultipartAlternativeMessage(
+          plainText: plainText,
+          htmlText: markdownToHtml(markdown),
+        )
+        ..subject = subject
+        ..from = [from]
+        ..to = [to],
+    );
+  }
+
   static final provider =
       AsyncNotifierProvider<MailClientController, MailClient>(
         MailClientController.new,