diff --git a/model/lib/email/attachment.dart b/model/lib/email/attachment.dart
index 4a8c690ee6..90b727089a 100644
--- a/model/lib/email/attachment.dart
+++ b/model/lib/email/attachment.dart
@@ -49,7 +49,7 @@ class Attachment with EquatableMixin {
       'name' : name ?? '',
       'type' : type?.mimeType ?? '',
     });
-    return Uri.decodeFull(downloadUri);
+    return downloadUri;
   }
 
   String generateFileName() {
diff --git a/model/test/email/attachment_test.dart b/model/test/email/attachment_test.dart
new file mode 100644
index 0000000000..b4f43a0024
--- /dev/null
+++ b/model/test/email/attachment_test.dart
@@ -0,0 +1,67 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http_parser/http_parser.dart';
+import 'package:jmap_dart_client/jmap/account_id.dart';
+import 'package:jmap_dart_client/jmap/core/id.dart';
+import 'package:model/email/attachment.dart';
+
+void main() {
+  final accountId = AccountId(Id('1'));
+  const baseDownloadUrl = 'http://localhost/download/{accountId}/{blobId}/{name}?name={name}&type={type}';
+
+  group('attachment test:', () {
+    group('getDownloadUrl:', () {
+      test(
+        'should return download url with blobId, name and type',
+      () {
+        // arrange
+        final attachment = Attachment(
+          blobId: Id('some-blob-id'),
+          name: 'some-name',
+          type: MediaType.parse('application/octet-stream'),
+        );
+        
+        // act
+        final result = attachment.getDownloadUrl(baseDownloadUrl, accountId);
+        
+        // assert
+        expect(result, 'http://localhost/download/1/some-blob-id/some-name?name=some-name&type=application%2Foctet-stream');
+      });
+
+      test(
+        'should return download url with blobId, name and type '
+        'when attachment name contains question mark character',
+      () {
+        // arrange
+        final attachment = Attachment(
+          blobId: Id('some-blob-id'),
+          name: 'some-name?',
+          type: MediaType.parse('application/octet-stream'),
+        );
+        
+        // act
+        final result = attachment.getDownloadUrl(baseDownloadUrl, accountId);
+        
+        // assert
+        expect(result, 'http://localhost/download/1/some-blob-id/some-name%3F?name=some-name%3F&type=application%2Foctet-stream');
+      });
+
+      test(
+        'should return download url with blobId, name and type '
+        'when attachment name is Vietnamese',
+      () {
+        // arrange
+        final attachment = Attachment(
+          blobId: Id('some-blob-id'),
+          name: 'tiêu đề attachment',
+          type: MediaType.parse('application/octet-stream'),
+        );
+        
+        // act
+        final result = attachment.getDownloadUrl(baseDownloadUrl, accountId);
+        
+        // assert
+        expect(result, 'http://localhost/download/1/some-blob-id/ti%C3%AAu%20%C4%91%E1%BB%81%20attachment?name=ti%C3%AAu%20%C4%91%E1%BB%81%20attachment&type=application%2Foctet-stream');
+      });
+    });
+  });
+}
\ No newline at end of file