From b1c04c5bad5f2d42ee5de8b98f1e06d99eb2223b Mon Sep 17 00:00:00 2001
From: Andrew Koryavchenko <avk@rsdn.org>
Date: Sat, 21 Oct 2017 16:10:57 +0300
Subject: [PATCH 1/2] C# usage sample

---
 README.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/README.md b/README.md
index 163d82b..9679e4e 100644
--- a/README.md
+++ b/README.md
@@ -86,6 +86,30 @@ rl.on('close', () => {
 });
 ```
 
+**C#**
+```C#
+private static readonly Lazy<HashSet<string>> _emailBlackList =
+  new Lazy<HashSet<string>>(
+    () =>
+    {
+      var result = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+      using (var reader = new StreamReader("disposable_email_blacklist.conf"))
+      {
+        string line;
+        while ((line = reader.ReadLine()) != null)
+          if (!string.IsNullOrWhiteSpace(line) && !line.TrimStart().StartsWith("//"))
+            result.Add(line);
+      }
+      return result;
+    });
+
+...
+
+var addr = new MailAddress(email);
+if (_emailBlackList.Value.Contains(addr.Host)))
+  throw new ApplicationException("Email is blacklisted.");
+```
+
 Contributing
 ============
 Feel free to create PR with additions or request removal of some domain (with reasons).

From 41ae31c0eb2e9020faae57bff8f4ce5b9a979b77 Mon Sep 17 00:00:00 2001
From: Andrew Koryavchenko <avk@rsdn.org>
Date: Mon, 23 Oct 2017 00:20:57 +0300
Subject: [PATCH 2/2] Fix C# sample

---
 README.md | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 9679e4e..31a4608 100644
--- a/README.md
+++ b/README.md
@@ -103,10 +103,20 @@ private static readonly Lazy<HashSet<string>> _emailBlackList =
       return result;
     });
 
+private static bool IsBlacklisted(string domain)
+{
+  var parts = domain.Split('.');
+  var len = parts.Length;
+  return
+    len == 1 && _emailBlackList.Value.Contains(domain)
+    || _emailBlackList.Value.Contains($"{parts[len - 2]}.{parts[len - 1]}")
+    || len > 2 && _emailBlackList.Value.Contains($"{parts[len - 3]}.{parts[len - 2]}.{parts[len - 1]}");
+}
+
 ...
 
 var addr = new MailAddress(email);
-if (_emailBlackList.Value.Contains(addr.Host)))
+if (IsBlacklisted(addr.Host)))
   throw new ApplicationException("Email is blacklisted.");
 ```