dotnet-core/release-notes/5.0/netstandard2.1/5.0-preview5_System.Net.Mail.md

System.Net.Mail

 namespace System.Net.Mail {
     public class MailAddress {
+        public static bool TryCreate(string address, out MailAddress result);
+        public static bool TryCreate(string address, string displayName, out MailAddress result);
+        public static bool TryCreate(string address, string displayName, Encoding displayNameEncoding, out MailAddress result);
     }
     public class SmtpClient : IDisposable {
+        public Task SendMailAsync(MailMessage message, CancellationToken cancellationToken);
+        public Task SendMailAsync(string from, string recipients, string subject, string body, CancellationToken cancellationToken);
     }
 }