adds unique constrain to the message id and a bit of a change on how to create a message

django_mailbox/migrations/0009_auto_20210207_0221.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.6 on 2021-02-07 02:21
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_mailbox', '0008_auto_20190219_1553'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='message',
+            name='message_id',
+            field=models.CharField(blank=None, max_length=255, null=None, unique=True, verbose_name='Message ID'),
+        ),
+    ]