Add model PresentationEmail

model/lib/extensions/email_address_extension.dart

@@ -0,0 +1,13 @@
+import 'package:jmap_dart_client/jmap/mail/email/email_address.dart';
+
+extension EmailAddressExtension on EmailAddress {
+
+  String asString() {
+    if (name != null && name!.isNotEmpty) {
+      return name!;
+    } else if (email != null && email!.isNotEmpty) {
+      return email!;
+    }
+    return '';
+  }
+}