Allow developers to specify a local IPEndPoint to use for connecting …

…to remote servers

Fixes issue #247

MailKit/IMailService.cs

@@ -76,6 +76,15 @@ public interface IMailService : IDisposable
 		/// </remarks>
 		/// <value>The server certificate validation callback function.</value>
 		RemoteCertificateValidationCallback ServerCertificateValidationCallback { get; set; }
+
+		/// <summary>
+		/// Get or set the local IP end point to use when connecting to the remote host.
+		/// </summary>
+		/// <remarks>
+		/// Gets or sets the local IP end point to use when connecting to the remote host.
+		/// </remarks>
+		/// <value>The local IP end point or <c>null</c> to use the default end point.</value>
+		IPEndPoint LocalEndPoint { get; set; }
 #endif
 
 		/// <summary>

MailKit/MailService.cs

@@ -175,6 +175,17 @@ public X509CertificateCollection ClientCertificates {
 		public RemoteCertificateValidationCallback ServerCertificateValidationCallback {
 			get; set;
 		}
+
+		/// <summary>
+		/// Get or set the local IP end point to use when connecting to the remote host.
+		/// </summary>
+		/// <remarks>
+		/// Gets or sets the local IP end point to use when connecting to the remote host.
+		/// </remarks>
+		/// <value>The local IP end point or <c>null</c> to use the default end point.</value>
+		public IPEndPoint LocalEndPoint {
+			get; set;
+		}
 #endif
 
 		/// <summary>

MailKit/Net/Imap/ImapClient.cs

@@ -1170,6 +1170,10 @@ static void ComputeDefaultValues (string host, ref int port, ref SecureSocketOpt
 
 				try {
 					cancellationToken.ThrowIfCancellationRequested ();
+
+					if (LocalEndPoint != null)
+						socket.Bind (LocalEndPoint);
+
 					socket.Connect (ipAddresses[i], port);
 					break;
 				} catch (OperationCanceledException) {

MailKit/Net/Pop3/Pop3Client.cs

@@ -752,6 +752,10 @@ static void ComputeDefaultValues (string host, ref int port, ref SecureSocketOpt
 
 				try {
 					cancellationToken.ThrowIfCancellationRequested ();
+
+					if (LocalEndPoint != null)
+						socket.Bind (LocalEndPoint);
+
 					socket.Connect (ipAddresses[i], port);
 					break;
 				} catch (OperationCanceledException) {

MailKit/Net/Smtp/SmtpClient.cs

@@ -782,6 +782,10 @@ static void ComputeDefaultValues (string host, ref int port, ref SecureSocketOpt
 
 				try {
 					cancellationToken.ThrowIfCancellationRequested ();
+
+					if (LocalEndPoint != null)
+						socket.Bind (LocalEndPoint);
+
 					socket.Connect (ipAddresses[i], port);
 					break;
 				} catch (OperationCanceledException) {