diff --git a/.gitignore b/.gitignore
index 6e96963..fa22f8b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -161,3 +161,6 @@ cython_debug/
 
 # E.g. copies of old dev database
 *.bkp
+
+# Database dumps
+/*.json
diff --git a/shiftregister/feedback/management/__init__.py b/shiftregister/feedback/management/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/shiftregister/feedback/management/commands/__init__.py b/shiftregister/feedback/management/commands/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/shiftregister/feedback/management/commands/notify.py b/shiftregister/feedback/management/commands/notify.py
new file mode 100644
index 0000000..66fc381
--- /dev/null
+++ b/shiftregister/feedback/management/commands/notify.py
@@ -0,0 +1,135 @@
+import json
+import pathlib
+import sys
+
+from django.core.management.base import BaseCommand, CommandError
+from django.template import Context, Template
+from phonenumber_field.phonenumber import PhoneNumber
+
+from shiftregister.app.models import Helper
+from shiftregister.messaging import Message, MessageType
+from shiftregister.messaging.outbound import send
+
+
+class Command(BaseCommand):
+    help = (
+        "Notify a list of phone numbers excluding those already found in the database."
+    )
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            "-n",
+            "--dry-run",
+            action="store_true",
+            help="print messages that would be sent, but do not actually send them",
+        )
+        parser.add_argument(
+            "numbers", help="path to numbers list as JSON", type=pathlib.Path
+        )
+
+    def handle(self, *args, **options):
+        with options["numbers"].open() as f:
+            numbers = json.load(f)
+
+        if not isinstance(numbers, list) or not all(
+            map(lambda o: isinstance(o, dict) and "phone" in o, numbers)
+        ):
+            raise CommandError(
+                "JSON document must be an array of objects containing (at least) the key 'phone'"
+            )
+
+        template = Template(sys.stdin.read().strip())
+
+        numbers_count = len(numbers)
+        existing_numbers = set(Helper.objects.values_list("phone", flat=True))
+        numbers = list(
+            filter(
+                lambda o: PhoneNumber.from_string(o["phone"]) not in existing_numbers,
+                numbers,
+            )
+        )
+
+        self.stderr.write(
+            self.style.WARNING(
+                f"{numbers_count-len(numbers)} already found in database"
+            )
+        )
+
+        messages = (
+            Message(
+                i,
+                recipient=o["phone"],
+                text=template.render(Context(o)),
+                type=MessageType.OUTBOUND,
+            )
+            for i, o in enumerate(numbers)
+        )
+
+        if options["dry_run"]:
+            messages = list(messages)
+
+            self.stderr.write(
+                self.style.WARNING(f"would send {len(messages)} message(s)")
+            )
+            self.stderr.write()
+
+            for message in messages:
+                if int(message.key) != 0:
+                    self.stderr.write()
+                    self.stderr.write(self.style.WARNING("---"))
+                    self.stderr.write()
+
+                self.stderr.write(self.style.WARNING(f"to: {message.recipient}"))
+                self.stderr.write(self.style.WARNING(f"length: {len(message.text)}"))
+                self.stderr.write()
+                self.stderr.write(self.style.WARNING(message.text))
+
+            if len(messages) > 0:
+                self.stderr.write()
+
+            return
+
+        all_messages = set(messages)
+        sent_messages = set()
+
+        self.stderr.write(
+            self.style.SUCCESS(
+                f"{'0'.rjust(len(str(len(all_messages))))} / {len(all_messages)}"
+            ),
+            ending="",
+        )
+
+        error = None
+        try:
+            for message in send(all_messages):
+                sent_messages.add(message)
+
+                self.stderr.write(
+                    self.style.SUCCESS(
+                        f"\r{str(len(sent_messages)).rjust(len(str(len(all_messages))))} / {len(all_messages)}"
+                    ),
+                    ending="",
+                )
+        except Exception as e:
+            error = e
+
+        self.stderr.write()
+        self.stderr.write(
+            self.style.WARNING(f"sent {len(sent_messages)} out of {len(all_messages)}")
+        )
+        self.stderr.write(
+            self.style.WARNING(f"numbers to which messages could not be sent:")
+        )
+        self.stdout.write(
+            self.style.ERROR(
+                json.dumps(
+                    [
+                        {"phone": message.recipient}
+                        for message in all_messages - sent_messages
+                    ]
+                )
+            )
+        )
+
+        if error:
+            raise CommandError(error)
diff --git a/shiftregister/messaging/message.py b/shiftregister/messaging/message.py
index e24fb02..98a534b 100644
--- a/shiftregister/messaging/message.py
+++ b/shiftregister/messaging/message.py
@@ -45,11 +45,10 @@ class Message:
         self.created_at = created_at
 
     def __eq__(self, other):
-        if other is None:
-            return False
-        elif isinstance(other, Message):
-            other = other.key
-        else:
-            other = str(other)
+        if isinstance(other, Message):
+            return self.key == other.key
 
-        return self.key == other
+        return NotImplemented
+
+    def __hash__(self):
+        return hash(self.key)