diff --git a/src/Microsoft.AspNetCore.Identity.Specification.Tests/IdentitySpecificationTestBase.cs b/src/Microsoft.AspNetCore.Identity.Specification.Tests/IdentitySpecificationTestBase.cs
index 85aae381db..bf5439411f 100644
--- a/src/Microsoft.AspNetCore.Identity.Specification.Tests/IdentitySpecificationTestBase.cs
+++ b/src/Microsoft.AspNetCore.Identity.Specification.Tests/IdentitySpecificationTestBase.cs
@@ -457,7 +457,6 @@ namespace Microsoft.AspNetCore.Identity.Test
             IdentityResultAssert.IsFailure(await manager.CreateAsync(user), _errorDescriber.InvalidEmail(email));
         }
 
-#if NET452
         /// <summary>
         /// Test.
         /// </summary>
@@ -476,7 +475,6 @@ namespace Microsoft.AspNetCore.Identity.Test
             manager.Options.User.RequireUniqueEmail = true;
             IdentityResultAssert.IsFailure(await manager.CreateAsync(user), _errorDescriber.InvalidEmail(email));
         }
-#endif
 
         /// <summary>
         /// Test.
diff --git a/src/Microsoft.AspNetCore.Identity.Specification.Tests/Microsoft.AspNetCore.Identity.Specification.Tests.csproj b/src/Microsoft.AspNetCore.Identity.Specification.Tests/Microsoft.AspNetCore.Identity.Specification.Tests.csproj
index 95669cb76d..96e4a89e23 100644
--- a/src/Microsoft.AspNetCore.Identity.Specification.Tests/Microsoft.AspNetCore.Identity.Specification.Tests.csproj
+++ b/src/Microsoft.AspNetCore.Identity.Specification.Tests/Microsoft.AspNetCore.Identity.Specification.Tests.csproj
@@ -19,4 +19,7 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
     <PackageReference Include="System.Linq.Queryable" Version="$(CoreFxVersion)" />
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
+  </ItemGroup>
 </Project>
diff --git a/src/Microsoft.AspNetCore.Identity/Microsoft.AspNetCore.Identity.csproj b/src/Microsoft.AspNetCore.Identity/Microsoft.AspNetCore.Identity.csproj
index 9c8232c9ae..aab666228f 100644
--- a/src/Microsoft.AspNetCore.Identity/Microsoft.AspNetCore.Identity.csproj
+++ b/src/Microsoft.AspNetCore.Identity/Microsoft.AspNetCore.Identity.csproj
@@ -11,5 +11,6 @@
     <PackageReference Include="Microsoft.AspNetCore.Cryptography.KeyDerivation" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.AspNetCore.Hosting.Abstractions" Version="1.2.0-*" />
     <PackageReference Include="Microsoft.Extensions.TaskCache.Sources" Version="1.2.0-*" PrivateAssets="All" />
+    <PackageReference Include="System.ComponentModel.Annotations" Version="$(CoreFxVersion)" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/src/Microsoft.AspNetCore.Identity/UserValidator.cs b/src/Microsoft.AspNetCore.Identity/UserValidator.cs
index af870f2462..7962902891 100644
--- a/src/Microsoft.AspNetCore.Identity/UserValidator.cs
+++ b/src/Microsoft.AspNetCore.Identity/UserValidator.cs
@@ -3,12 +3,8 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
-#if NET451
-using System.Net.Mail;
-#endif
-using System.Text.RegularExpressions;
-using System.Threading;
 using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Identity
@@ -91,17 +87,11 @@ namespace Microsoft.AspNetCore.Identity
                 errors.Add(Describer.InvalidEmail(email));
                 return;
             }
-#if NET451
-            try
-            {
-                var m = new MailAddress(email);
-            }
-            catch (FormatException)
+            if (!new EmailAddressAttribute().IsValid(email))
             {
                 errors.Add(Describer.InvalidEmail(email));
                 return;
             }
-#endif
             var owner = await manager.FindByEmailAsync(email);
             if (owner != null && 
                 !string.Equals(await manager.GetUserIdAsync(owner), await manager.GetUserIdAsync(user)))
diff --git a/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test.csproj b/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test.csproj
index 176d11a255..b51447cd2b 100644
--- a/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test.csproj
+++ b/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.InMemory.Test.csproj
@@ -22,4 +22,7 @@
     <PackageReference Include="xunit" Version="2.2.0-*" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0-*" />
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
+  </ItemGroup>
 </Project>
diff --git a/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test.csproj b/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test.csproj
index 872148a0de..c16fab27d1 100644
--- a/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test.csproj
+++ b/test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test/Microsoft.AspNetCore.Identity.EntityFrameworkCore.Test.csproj
@@ -28,4 +28,7 @@
     <PackageReference Include="xunit" Version="2.2.0-*" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0-*" />
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
+  </ItemGroup>
 </Project>
diff --git a/test/Microsoft.AspNetCore.Identity.Test/Microsoft.AspNetCore.Identity.Test.csproj b/test/Microsoft.AspNetCore.Identity.Test/Microsoft.AspNetCore.Identity.Test.csproj
index 8402aff518..1054b89fb4 100644
--- a/test/Microsoft.AspNetCore.Identity.Test/Microsoft.AspNetCore.Identity.Test.csproj
+++ b/test/Microsoft.AspNetCore.Identity.Test/Microsoft.AspNetCore.Identity.Test.csproj
@@ -22,4 +22,7 @@
     <PackageReference Include="xunit" Version="2.2.0-*" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0-*" />
   </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
+  </ItemGroup>
 </Project>