diff --git a/app/main/views/send.py b/app/main/views/send.py
index 354c5c8e2..b1a1cc53e 100644
--- a/app/main/views/send.py
+++ b/app/main/views/send.py
@@ -439,7 +439,10 @@ def _check_messages(service_id, template_type, upload_id, letters_as_pdf=False):
         remaining_messages=remaining_messages,
         choose_time_form=choose_time_form,
         back_link=back_link,
-        help=get_help_argument()
+        help=get_help_argument(),
+        trying_to_send_letters_in_trial_mode=bool(
+            current_service['restricted'] and template.template_type == 'letter'
+        ),
     )
 
 
@@ -454,7 +457,8 @@ def check_messages(service_id, template_type, upload_id):
         data['recipients'].too_many_rows or
         not data['count_of_recipients'] or
         not data['recipients'].has_recipient_columns or
-        data['recipients'].missing_column_headers
+        data['recipients'].missing_column_headers or
+        data['trying_to_send_letters_in_trial_mode']
     ):
         return render_template('views/check/column-errors.html', **data)
 
diff --git a/app/templates/views/check/column-errors.html b/app/templates/views/check/column-errors.html
index f8407792f..491eade0f 100644
--- a/app/templates/views/check/column-errors.html
+++ b/app/templates/views/check/column-errors.html
@@ -75,14 +75,29 @@
         </p>
 
       {% elif not recipients.allowed_to_send_to %}
+
         {% with
           count_of_recipients=count_of_recipients,
           template_type_label=recipients.recipient_column_headers[0]
         %}
           {% include "partials/check/not-allowed-to-send-to.html" %}
         {% endwith %}
+
+      {% elif trying_to_send_letters_in_trial_mode %}
+
+        <h1 class='banner-title' data-module="track-error" data-error-type="Trying to send letters in trial mode" data-error-label="{{ upload_id }}">
+          You can’t send
+          {{ 'this letter' if count_of_recipients == 1 else 'these letters' }}
+        </h1>
+        <p>
+          In <a href="{{ url_for('.trial_mode') }}">trial mode</a> you
+          can only preview how your letters will look
+        </p>
+
       {% elif recipients.more_rows_than_can_send %}
+
         {% include "partials/check/too-many-messages.html" %}
+
       {% endif %}
 
       {{ skip_to_file_contents() }}
diff --git a/app/templates/views/trial-mode.html b/app/templates/views/trial-mode.html
index 73fe27c11..a3e90e3fe 100644
--- a/app/templates/views/trial-mode.html
+++ b/app/templates/views/trial-mode.html
@@ -17,7 +17,7 @@
     </p>
     <ul class="list list-bullet">
       <li>
-        you can only send messages to yourself
+        you can only send text messages and emails to yourself
       </li>
       <li>
         you can add people to
@@ -26,10 +26,13 @@
         {% else %}
           your team,
         {% endif %}
-        then you can send messages to them too
+        then you can send text messages and emails to them too
       </li>
       <li>
-        you can only send 50 messages per day
+        you can only send 50 text messages or emails per day
+      </li>
+      <li>
+        you can’t send any letters
       </li>
     </ul>
 
diff --git a/tests/app/main/views/test_send.py b/tests/app/main/views/test_send.py
index 4b56a17f1..06504e8c0 100644
--- a/tests/app/main/views/test_send.py
+++ b/tests/app/main/views/test_send.py
@@ -24,6 +24,8 @@ from tests.conftest import (
     mock_get_service_email_template,
     normalize_spaces,
     SERVICE_ONE_ID,
+    mock_get_service,
+    mock_get_live_service,
 )
 
 template_types = ['email', 'sms']
@@ -1577,6 +1579,58 @@ def test_check_messages_shows_trial_mode_error(
     )
 
 
+@pytest.mark.parametrize('service_mock, error_should_be_shown', [
+    (mock_get_service, True),
+    (mock_get_live_service, False),
+])
+@pytest.mark.parametrize('number_of_rows, expected_error_message', [
+    (1, 'You can’t send this letter'),
+    (111, 'You can’t send these letters'),
+])
+def test_check_messages_shows_trial_mode_error_for_letters(
+    client_request,
+    api_user_active,
+    mock_get_service_letter_template,
+    mock_has_permissions,
+    mock_get_users_by_service,
+    mock_get_detailed_service_for_today,
+    mocker,
+    service_mock,
+    error_should_be_shown,
+    number_of_rows,
+    expected_error_message,
+):
+
+    service_mock(mocker, api_user_active)
+
+    mocker.patch('app.main.views.send.s3download', return_value='\n'.join(
+        ['address_line_1,address_line_2,postcode,'] +
+        ['First Last,    123 Street,    SW1 1AA'] * number_of_rows
+    ))
+
+    with client_request.session_transaction() as session:
+        session['upload_data'] = {'template_id': ''}
+
+    page = client_request.get(
+        'main.check_messages',
+        service_id=SERVICE_ONE_ID,
+        template_type='letter',
+        upload_id=uuid.uuid4(),
+        _test_page_title=False,
+    )
+
+    error = page.select('.banner-dangerous')
+
+    if error_should_be_shown:
+        assert normalize_spaces(error[0].text) == (
+            '{} '
+            'In trial mode you can only preview how your letters will look '
+            'Skip to file contents'
+        ).format(expected_error_message)
+    else:
+        assert not error
+
+
 def test_check_messages_shows_over_max_row_error(
     logged_in_client,
     api_user_active,
@@ -1620,7 +1674,7 @@ def test_non_ascii_characters_in_letter_recipients_file_shows_error(
     api_user_active,
     mock_login,
     mock_get_users_by_service,
-    mock_get_service,
+    mock_get_live_service,
     mock_has_permissions,
     mock_get_service_letter_template,
     mock_get_detailed_service_for_today,