diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index a53cc9b..9b86a2a 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -11,6 +11,7 @@
 from io import StringIO, BytesIO
 from itertools import chain
 from random import choice
+from socket import getfqdn
 try:
     from threading import Thread
 except ImportError:
@@ -3294,6 +3295,17 @@
             email.utils.make_msgid(domain='testdomain-string')[-19:],
             '@testdomain-string>')
 
+    def test_make_msgid_idstring(self):
+        self.assertEqual(
+            email.utils.make_msgid(idstring='test-idstring',
+                domain='testdomain-string')[-33:],
+            '.test-idstring@testdomain-string>')
+
+    def test_make_msgid_default_domain(self):
+        self.assertTrue(
+            email.utils.make_msgid().endswith(
+                '@' + getfqdn() + '>'))
+
     def test_Generator_linend(self):
         # Issue 14645.
         with openfile('msg_26.txt', newline='\n') as f:
diff --git a/Misc/ACKS b/Misc/ACKS
index 08d06e7..a9cd72e 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -187,6 +187,7 @@
 Anthony Briggs
 Keith Briggs
 Tobias Brink
+Dillon Brock
 Richard Brodie
 Michael Broghton
 Ammar Brohi