diff --git a/app/dao/notifications_dao.py b/app/dao/notifications_dao.py
index 3eb999d3b..3f46577b3 100644
--- a/app/dao/notifications_dao.py
+++ b/app/dao/notifications_dao.py
@@ -1,5 +1,4 @@
 import functools
-import string
 from itertools import groupby
 from operator import attrgetter
 from datetime import (
@@ -570,8 +569,6 @@ def dao_update_notifications_by_reference(references, update_dict):
 
 @statsd(namespace="dao")
 def dao_get_notifications_by_recipient_or_reference(service_id, search_term, notification_type=None, statuses=None):
-    if notification_type is None:
-        notification_type = guess_notification_type(search_term)
 
     if notification_type == SMS_TYPE:
         normalised = try_validate_and_format_phone_number(search_term)
@@ -587,9 +584,12 @@ def dao_get_notifications_by_recipient_or_reference(service_id, search_term, not
         except InvalidEmailError:
             normalised = search_term.lower()
 
-    else:
+    elif notification_type == LETTER_TYPE:
         raise InvalidRequest("Only email and SMS can use search by recipient", 400)
 
+    else:
+        normalised = search_term.lower()
+
     normalised = escape_special_characters(normalised)
     search_term = escape_special_characters(search_term)
 
@@ -765,13 +765,6 @@ def dao_precompiled_letters_still_pending_virus_check():
     return notifications
 
 
-def guess_notification_type(search_term):
-    if set(search_term) & set(string.ascii_letters + '@'):
-        return EMAIL_TYPE
-    else:
-        return SMS_TYPE
-
-
 def _duplicate_update_warning(notification, status):
     current_app.logger.info(
         (
diff --git a/app/service/rest.py b/app/service/rest.py
index 60141e87e..7cdd259d5 100644
--- a/app/service/rest.py
+++ b/app/service/rest.py
@@ -455,7 +455,7 @@ def cancel_notification_for_service(service_id, notification_id):
 
 
 def search_for_notification_by_to_field(service_id, search_term, statuses, notification_type):
-    results = notifications_dao.dao_get_notifications_by_to_field(
+    results = notifications_dao.dao_get_notifications_by_recipient_or_reference(
         service_id=service_id,
         search_term=search_term,
         statuses=statuses,
diff --git a/tests/app/dao/notification_dao/test_notification_dao.py b/tests/app/dao/notification_dao/test_notification_dao.py
index 546288c2c..7cfa9e76e 100644
--- a/tests/app/dao/notification_dao/test_notification_dao.py
+++ b/tests/app/dao/notification_dao/test_notification_dao.py
@@ -1272,18 +1272,23 @@ def test_dao_get_notifications_by_recipient_searches_across_notification_types(
     email = create_notification(
         template=email_template, to_field='077@example.com', normalised_to='077@example.com'
     )
-    results = dao_get_notifications_by_recipient_or_reference(service.id, phone_search, notification_type='sms')
+
+    results = dao_get_notifications_by_recipient_or_reference(
+        service.id, phone_search, notification_type='sms'
+    )
     assert len(results) == 1
     assert results[0].id == sms.id
-    results = dao_get_notifications_by_recipient_or_reference(service.id, phone_search)  # should assume SMS
-    assert len(results) == 1
-    assert results[0].id == sms.id
-    results = dao_get_notifications_by_recipient_or_reference(service.id, '077', notification_type='email')
+
+    results = dao_get_notifications_by_recipient_or_reference(
+        service.id, email_search, notification_type='email'
+    )
     assert len(results) == 1
     assert results[0].id == email.id
-    results = dao_get_notifications_by_recipient_or_reference(service.id, email_search)  # should assume email
-    assert len(results) == 1
+
+    results = dao_get_notifications_by_recipient_or_reference(service.id, '77')
+    assert len(results) == 2
     assert results[0].id == email.id
+    assert results[1].id == sms.id
 
 
 def test_dao_get_notifications_by_reference(
@@ -1307,10 +1312,11 @@ def test_dao_get_notifications_by_reference(
 
     results = dao_get_notifications_by_recipient_or_reference(service.id, '77')
     assert len(results) == 2
-    assert results[0].id == sms.id
     assert results[0].id == email.id
+    assert results[1].id == sms.id
+
     # If notification_type isn’t specified then we can’t normalise the phone number
-    # to 4477… so this query will only find the email
+    # to 4477… so this query will only find the email sent to 077@example.com
     results = dao_get_notifications_by_recipient_or_reference(service.id, '077')
     assert len(results) == 1
     assert results[0].id == email.id
@@ -1318,21 +1324,26 @@ def test_dao_get_notifications_by_reference(
     results = dao_get_notifications_by_recipient_or_reference(service.id, '077', notification_type='sms')
     assert len(results) == 1
     assert results[0].id == sms.id
+
     results = dao_get_notifications_by_recipient_or_reference(service.id, '77', notification_type='sms')
     assert len(results) == 1
     assert results[0].id == sms.id
+
     results = dao_get_notifications_by_recipient_or_reference(service.id, 'Aa', notification_type='sms')
     assert len(results) == 1
     assert results[0].id == sms.id
+
     results = dao_get_notifications_by_recipient_or_reference(service.id, 'bB', notification_type='sms')
     assert len(results) == 0
 
     results = dao_get_notifications_by_recipient_or_reference(service.id, '77', notification_type='email')
     assert len(results) == 1
     assert results[0].id == email.id
+
     results = dao_get_notifications_by_recipient_or_reference(service.id, 'Bb', notification_type='email')
     assert len(results) == 1
     assert results[0].id == email.id
+
     results = dao_get_notifications_by_recipient_or_reference(service.id, 'aA', notification_type='email')
     assert len(results) == 0