diff --git a/Rnwood.Smtp4dev.Tests/Rnwood.Smtp4dev.Tests.csproj b/Rnwood.Smtp4dev.Tests/Rnwood.Smtp4dev.Tests.csproj
index d45670c56..62d14fa6a 100644
--- a/Rnwood.Smtp4dev.Tests/Rnwood.Smtp4dev.Tests.csproj
+++ b/Rnwood.Smtp4dev.Tests/Rnwood.Smtp4dev.Tests.csproj
@@ -25,7 +25,7 @@
 
   <ItemGroup>
     <PackageReference Include="FluentAssertions" Version="6.2.0" />
-    <PackageReference Include="MailKit" Version="2.15.0" />
+    <PackageReference Include="MailKit" Version="3.4.2" />
     <PackageReference Include="MedallionShell" Version="1.6.2" />
     <PackageReference Include="NSubstitute" Version="4.2.2" />
     <PackageReference Include="ReflectionMagic" Version="4.1.0" />
diff --git a/Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj b/Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj
index 1e42af762..eeb6e4f64 100644
--- a/Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj
+++ b/Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj
@@ -23,7 +23,7 @@
 		<PackageReference Include="Ardalis.GuardClauses" Version="3.3.0" />
 		<PackageReference Include="CommandLiners.MonoOptions" Version="1.0.36" />
 		<PackageReference Include="HtmlAgilityPack" Version="1.11.40" />
-		<PackageReference Include="MailKit" Version="2.15.0" />
+		<PackageReference Include="MailKit" Version="3.4.2" />
 		<PackageReference Include="Microsoft.AspNetCore.Hosting.WindowsServices" Version="3.1.20" />
 		<PackageReference Include="Microsoft.AspNetCore.SignalR" Version="1.1.0" />
 		<PackageReference Include="Microsoft.AspNetCore.SignalR.Core" Version="1.1.0" />