diff --git a/zephyr/models.py b/zephyr/models.py
index 5bc34bbfd5..5ce737b276 100644
--- a/zephyr/models.py
+++ b/zephyr/models.py
@@ -24,6 +24,7 @@ import re
 from django.utils.html import escape
 
 MAX_SUBJECT_LENGTH = 60
+MAX_MESSAGE_LENGTH = 10000
 
 @cache_with_key(lambda self: 'display_recipient_dict:%d' % (self.id,))
 def get_display_recipient(recipient):
@@ -556,7 +557,9 @@ def do_send_message(message, no_log=False):
             users    = simplejson.dumps([str(user.id) for user in recipients])))
 
 def internal_send_message(sender_email, recipient_type, recipient_name,
-        subject, content):
+                          subject, content):
+    if len(content) > MAX_MESSAGE_LENGTH:
+        content = content[0:3900] + "\n\n[message was too long and has been truncated]"
     message = Message()
     message.sender = UserProfile.objects.get(user__email=sender_email)
     message.recipient = Recipient.objects.get(type_id=create_stream_if_needed(
diff --git a/zephyr/views.py b/zephyr/views.py
index ea8b03cf47..8805f62dbb 100644
--- a/zephyr/views.py
+++ b/zephyr/views.py
@@ -17,7 +17,7 @@ from zephyr.models import Message, UserProfile, Stream, Subscription, \
     create_mit_user_if_needed, create_stream_if_needed, StreamColor, \
     PreregistrationUser, get_client, MitUser, User, UserActivity, \
     log_subscription_property_change, internal_send_message, \
-    MAX_SUBJECT_LENGTH
+    MAX_SUBJECT_LENGTH, MAX_MESSAGE_LENGTH
 from zephyr.forms import RegistrationForm, HomepageForm, is_unique, \
     is_active
 from django.views.decorators.csrf import csrf_exempt
@@ -607,6 +607,8 @@ def send_message_backend(request, user_profile, client,
 
     if len(message_to) == 0:
         return json_error("Message must have recipients.")
+    if len(message_content) > MAX_MESSAGE_LENGTH:
+        return json_error("Message too long.")
 
     if client.name == "zephyr_mirror":
         # Here's how security works for non-superuser mirroring: