diff --git a/test/Core.Test/Utilities/StrictEmailAddressListAttributeTests.cs b/test/Core.Test/Utilities/StrictEmailAddressListAttributeTests.cs
new file mode 100644
index 0000000000..2280fbb6c7
--- /dev/null
+++ b/test/Core.Test/Utilities/StrictEmailAddressListAttributeTests.cs
@@ -0,0 +1,55 @@
+using System.Collections.Generic;
+using Bit.Core.Utilities;
+using Xunit;
+
+namespace Bit.Core.Test.Utilities
+{
+    public class StrictEmailAddressListAttributeTests
+    {
+        public static List<object[]> EmailList => new()
+        {
+            new object[] { new List<string> { "test@domain.com", "test@sub.domain.com", "hello@world.planet.com" }, true },
+            new object[] { new List<string> { "/hello@world.com", "hello@##world.pla   net.com", "''thello@world.com" }, false },
+            new object[] { new List<string> { "/hello.com", "test@domain.com", "''thello@world.com" }, false },
+            new object[] { new List<string> { "héllö@world.com", "hello@world.planet.com", "hello@world.planet.com" }, false },
+            new object[] { new List<string> { }, false },
+            new object[] { new List<string>
+                {
+                    "test1@domain.com", "test2@domain.com", "test3@domain.com", "test4@domain.com", "test5@domain.com",
+                    "test6@domain.com", "test7@domain.com", "test8@domain.com", "test9@domain.com", "test10@domain.com",
+                    "test11@domain.com", "test12@domain.com", "test13@domain.com", "test14@domain.com", "test15@domain.com",
+                    "test16@domain.com", "test17@domain.com", "test18@domain.com", "test19@domain.com", "test20@domain.com",
+                    "test21@domain.com", "test22@domain.com", "test23@domain.com", "test24@domain.com", "test25@domain.com",
+                }, false },
+            new object[] { new List<string>
+                {
+                    "test1domaincomtest2domaincomtest3domaincomtest4domaincomtest5domaincomtest6domaincomtest7domaincomtest8domaincomtest9domaincomtest10domaincomtest1domaincomtest2domaincomtest3domaincomtest4domaincomtest5domaincomtest6domaincomtest7domaincomtest8domaincomtest9domaincomtest10domaincom@test.com",
+                    "test@domain.com"
+                }, false } // > 256 character email
+
+        };
+
+        [Theory]
+        [MemberData(nameof(EmailList))]
+        public void IsListValid_ReturnsTrue_WhenValid(List<string> emailList, bool valid)
+        {
+            var sut = new StrictEmailAddressListAttribute();
+
+            var actual = sut.IsValid(emailList);
+
+            Assert.Equal(actual, valid);
+        }
+
+        [Theory]
+        [InlineData("single@email.com", false)]
+        [InlineData(null, false)]
+        public void IsValid_ReturnsTrue_WhenValid(string email, bool valid)
+        {
+            var sut = new StrictEmailAddressListAttribute();
+
+            var actual = sut.IsValid(email);
+
+            Assert.Equal(actual, valid);
+        }
+    }
+}