diff --git a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJob.cs b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJob.cs
index 9a70469df8..07b4ca9bcd 100644
--- a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJob.cs
+++ b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJob.cs
@@ -23,7 +23,7 @@ public class BackgroundEmailSendingJob : AsyncBackgroundJob<BackgroundEmailSendi
         }
         else
         {
-            await EmailSender.SendAsync(args.From, args.To, args.Subject, args.Body, args.IsBodyHtml);
+            await EmailSender.SendAsync(args.From!, args.To, args.Subject, args.Body, args.IsBodyHtml);
         }
     }
 }
diff --git a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJobArgs.cs b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJobArgs.cs
index edfd1fefa5..884f219763 100644
--- a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJobArgs.cs
+++ b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/BackgroundEmailSendingJobArgs.cs
@@ -5,13 +5,13 @@ namespace Volo.Abp.Emailing;
 [Serializable]
 public class BackgroundEmailSendingJobArgs
 {
-    public string From { get; set; }
+    public string? From { get; set; }
 
-    public string To { get; set; }
+    public string To { get; set; } = default!;
 
-    public string Subject { get; set; }
+    public string? Subject { get; set; }
 
-    public string Body { get; set; }
+    public string? Body { get; set; }
 
     /// <summary>
     /// Default: true.
diff --git a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
index 81a381c975..d8a46ca4b9 100644
--- a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
+++ b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/EmailSenderBase.cs
@@ -24,7 +24,7 @@ public abstract class EmailSenderBase : IEmailSender
         BackgroundJobManager = backgroundJobManager;
     }
 
-    public virtual async Task SendAsync(string to, string subject, string body, bool isBodyHtml = true)
+    public virtual async Task SendAsync(string to, string? subject, string? body, bool isBodyHtml = true)
     {
         await SendAsync(new MailMessage
         {
@@ -35,7 +35,7 @@ public abstract class EmailSenderBase : IEmailSender
         });
     }
 
-    public virtual async Task SendAsync(string from, string to, string subject, string body, bool isBodyHtml = true)
+    public virtual async Task SendAsync(string from, string to, string? subject, string? body, bool isBodyHtml = true)
     {
         await SendAsync(new MailMessage(from, to, subject, body) { IsBodyHtml = isBodyHtml });
     }
diff --git a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/IEmailSender.cs b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/IEmailSender.cs
index 016f4f6be4..55456783c4 100644
--- a/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/IEmailSender.cs
+++ b/framework/src/Volo.Abp.Emailing/Volo/Abp/Emailing/IEmailSender.cs
@@ -13,8 +13,8 @@ public interface IEmailSender
     /// </summary>
     Task SendAsync(
         string to,
-        string subject,
-        string body,
+        string? subject,
+        string? body,
         bool isBodyHtml = true
     );
 
@@ -24,8 +24,8 @@ public interface IEmailSender
     Task SendAsync(
         string from,
         string to,
-        string subject,
-        string body,
+        string? subject,
+        string? body,
         bool isBodyHtml = true
     );
 
diff --git a/framework/src/Volo.Abp.MailKit/Volo.Abp.MailKit.csproj b/framework/src/Volo.Abp.MailKit/Volo.Abp.MailKit.csproj
index bec6f35355..5d3d7d660c 100644
--- a/framework/src/Volo.Abp.MailKit/Volo.Abp.MailKit.csproj
+++ b/framework/src/Volo.Abp.MailKit/Volo.Abp.MailKit.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.MailKit</AssemblyName>
     <PackageId>Volo.Abp.MailKit</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>