Merge pull request CodeCowboyOrg#4 from kevgeni/sslversion

Add combobox to select ssl/tsl version.

Author: CodeCowboyOrg

README.md

@@ -5,7 +5,7 @@
 1. Download the release under the "release" tab.
 2. Supports Basic Authentication to SMTP server.
 3. Supports Anonymous connection to SMTP Server.
-4. Supports SSL connection to SMTP server.
+4. Supports SSL connection to SMTP server in STARTSSL mode only. Does not support connecting to SMTP/SSL, SMTP over SSL, or SMTPS server on default port 465.
 5. Runs on Windows.
 
 ![Image of Software](https://i.imgur.com/Z7NCEcm.png)

SimpleSmtpClient/Form1.Designer.cs

@@ -44,6 +44,29 @@ private void guiSendMail_Click(object sender, EventArgs e)
                 if (guiUseSsl.Checked)
                 {
                     client.EnableSsl = true;
+
+                    int sslVer = cmbSSLVersion.SelectedIndex;
+                    if (sslVer == 0 || sslVer == -1)
+                    {
+                        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.SystemDefault;
+                    }
+                    else if (sslVer == 1)
+                    {
+                        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
+                    }
+                    else if (sslVer == 2)
+                    {
+                        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
+                    }
+                    else if (sslVer == 3)
+                    {
+                        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11;
+                    }
+                    else if (sslVer == 4)
+                    {
+                        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
+                    }
+                    //tls 1.3 not supported by .net framework 4.8 as of now.
                 }
                 MailMessage message = CreateMailMessage();
                 client.Send(message);

SimpleSmtpClient/Form1.cs

@@ -112,12 +112,12 @@
     <value>2.0</value>
   </resheader>
   <resheader name="reader">
-    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <resheader name="writer">
-    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
-  <assembly alias="System.Drawing" name="System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
+  <assembly alias="System.Drawing" name="System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
   <data name="$this.Icon" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
     <value>
         AAABAAkAAAAAAAEAIABWTgAAlgAAAICAAAABACAAKAgBAOxOAABgYAAAAQAgAKiUAAAUVwEASEgAAAEA

SimpleSmtpClient/Form1.resx

@@ -32,5 +32,5 @@
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]
+[assembly: AssemblyVersion("2.0.0.0")]
+[assembly: AssemblyFileVersion("2.0.0.0")]

SimpleSmtpClient/Properties/AssemblyInfo.cs

@@ -9,7 +9,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>SimpleSmtpClient</RootNamespace>
     <AssemblyName>SimpleSmtpClient</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <TargetFrameworkProfile />
   </PropertyGroup>
@@ -22,6 +22,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -31,6 +32,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />

SimpleSmtpClient/Properties/Resources.Designer.cs

@@ -1,3 +1,3 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
-<startup><supportedRuntime version="v2.0.50727"/></startup></configuration>
+<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.8"/></startup></configuration>