diff --git a/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj b/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
index 7057c2c44..a23687eed 100644
--- a/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
+++ b/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
@@ -52,10 +52,10 @@
     <Reference Include="System.Data" />
     <Reference Include="System.Security" />
     <Reference Include="MimeKit">
-      <HintPath>..\..\..\..\packages\MimeKit.1.16.1\lib\net45\MimeKit.dll</HintPath>
+      <HintPath>..\..\..\..\packages\MimeKit.1.18.1\lib\net45\MimeKit.dll</HintPath>
     </Reference>
     <Reference Include="MailKit">
-      <HintPath>..\..\..\..\packages\MailKit.1.16.1\lib\net45\MailKit.dll</HintPath>
+      <HintPath>..\..\..\..\packages\MailKit.1.18.1.1\lib\net45\MailKit.dll</HintPath>
     </Reference>
     <Reference Include="Newtonsoft.Json">
       <HintPath>..\..\..\..\packages\Newtonsoft.Json.10.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
diff --git a/Duplicati/Library/Modules/Builtin/packages.config b/Duplicati/Library/Modules/Builtin/packages.config
index b2fb2a76e..75d5024ea 100644
--- a/Duplicati/Library/Modules/Builtin/packages.config
+++ b/Duplicati/Library/Modules/Builtin/packages.config
@@ -2,7 +2,7 @@
 <packages>
   <package id="agsXMPP" version="1.1.1.0" targetFramework="net45" />
   <package id="BouncyCastle" version="1.8.1" targetFramework="net45" />
-  <package id="MailKit" version="1.16.1" targetFramework="net45" />
-  <package id="MimeKit" version="1.16.1" targetFramework="net45" />
+  <package id="MailKit" version="1.18.1.1" targetFramework="net45" />
+  <package id="MimeKit" version="1.18.1" targetFramework="net45" />
   <package id="Newtonsoft.Json" version="10.0.3" targetFramework="net45" />
 </packages>
\ No newline at end of file