Added support for Inline images for MailGun

src/FluentEmail.Core/Models/Attachment.cs

@@ -8,6 +8,10 @@ namespace FluentEmail.Core.Models
 {
     public class Attachment
     {
+        /// <summary>
+        /// Gets or sets whether the attachment is intended to be used for inline images (changes the paramater name for providers such as MailGun)
+        /// </summary>
+        public bool IsInline { get; set; }
         public string Filename { get; set; }
         public Stream Data { get; set; }
         public string ContentType { get; set; }

src/Senders/FluentEmail.Mailgun/MailgunSender.cs

@@ -63,9 +63,16 @@ public async Task<SendResponse> SendAsync(Email email, CancellationToken? token
             var files = new List<HttpFile>();
             email.Data.Attachments.ForEach(x =>
             {
+                string param;
+
+                if (x.IsInline)
+                    param = "inline";
+                else
+                    param = "attachment";
+
                 files.Add(new HttpFile()
                 {
-                    ParameterName = "attachment",
+                    ParameterName = param,
                     Data = x.Data,
                     Filename = x.Filename,
                     ContentType = x.ContentType

test/FluentEmail.Mailgun.Tests/FluentEmail.Mailgun.Tests.csproj

@@ -6,6 +6,14 @@
     <PackageId>FluentEmail.Mailgun.Tests</PackageId>
   </PropertyGroup>
 
+  <ItemGroup>
+    <None Remove="logotest.png" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Include="logotest.png" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.3.0-preview-20170502-03" />
     <PackageReference Include="NUnit" Version="3.6.1" />

test/FluentEmail.Mailgun.Tests/MailgunSenderTests.cs

@@ -3,6 +3,7 @@
 using FluentEmail.Core;
 using FluentEmail.Core.Models;
 using NUnit.Framework;
+using System.Reflection;
 
 namespace FluentEmail.Mailgun.Tests
 {
@@ -61,5 +62,35 @@ public async Task CanSendEmailWithAttachments()
 
             Assert.IsTrue(response.Successful);
         }
+
+        [Test]
+        public async Task CanSendEmailWithInlineImages()
+        {
+            var assembly = Assembly.GetExecutingAssembly();
+            var stream = assembly.GetManifestResourceStream(assembly.GetName().Name + ".logotest.png");
+            stream.Flush();
+
+            stream.Seek(0, SeekOrigin.Begin);
+
+            var attachment = new Attachment()
+            {
+                IsInline = true,
+                Data = stream,
+                ContentType = "image/png",
+                Filename = "logotest.png"
+            };
+
+            var email = Email
+                .From(fromEmail)
+                .To(toEmail)
+                .Subject(subject)
+                .Body("<html>Inline image here: <img src=\"cid:logotest.png\">" +
+                "<p>You should see an image without an attachment, or without a download prompt, dependig on the email client.</p></html>", true)
+                .Attach(attachment);
+
+            var response = await email.SendAsync();
+
+            Assert.IsTrue(response.Successful);
+        }
     }
 }