diff --git a/Michaelsoft.Mailer.csproj b/Michaelsoft.Mailer.csproj
index e69155c..dcfcbbb 100644
--- a/Michaelsoft.Mailer.csproj
+++ b/Michaelsoft.Mailer.csproj
@@ -17,7 +17,7 @@
     <ItemGroup>
         <PackageReference Include="MailKit" Version="2.8.0" />
         <PackageReference Include="Microsoft.Extensions.Options" Version="3.1.5" />
-        <PackageReference Include="MimeKit" Version="2.9.1" />
+        <PackageReference Include="MimeKit" Version="4.15.1" />
     </ItemGroup>
 
 </Project>