New Seafile Add-In for Microsoft Outlook ready-for-testing

Integrate your favorite File Collaboration solution Seafile and Microsoft Outlook with the new Seafile add-in for Microsoft Outlook. A ready-for-testing version is now available for download at The add-in was developed by datamate, European Seafile Partner, and freelance developer Simon Giesen.


The add-in supports:

  • Create sharing links (with password/expiration) directly from the mail window
  • Insert existing sharing links in emails
  • Upload file attachments to a folder/library
  • Upload an email’s as an HTML file to a folder/library
  • Switch to Seahub with one click - no login required

Authentication with username/password and single-sign on (SSO) is supported. The password/token is stored in a JSON-formatted cfg-file in Windows’s hidden AppData folder. (Depending on the system’s configuration, the file is either saved in the Roaming or Local folder.) The password/token is protected with .NET’s DataProtectionProvider Class against the Local User Windows Certificate. The file itself is unencrypted.


The add-in is compatible with Microsoft Outlook 2010 and later as well as Office 365. The add-in was tested extensively on Windows 10 computers.

Extract the files from the package and run the setup.exe. If not already installed on the computer, the .NET Framework 3.5 is installed as the only prerequisite.

Further development and release

The add-in is version 0.9 and under development by datamate. At this point, the upload of emails and email attachments still requires a local folder at C:\seafile. The English translation is WIP.

The test period runs for 2 weeks. Post you feedback underneath. A production ready version will be released under an open-source license in the weeks thereafter on GitHub.

datamate considers developing an enterprise-ready add-in supporting custom branding and automatic deployment. Interested? Please contact us at!


Hey, this sounds awesome.
Unfortunately, it won’t work in my setup. Installation runs fine but I can’t login to my server (wrong credentials).

Looking to my nginx error.log I can see some SSL handshake issue.
2020/03/28 10:47:35 [crit] 1299#1299: *49056 SSL_do_handshake() failed (SSL: error:14209102:SSL routines:tls_early_post_process_client_hello:unsupported protocol) while SSL handshaking, client:, server:
My server is configured to SSLlab’s recommendations and achieves a solid A+ there. Let me know if you need any config details (only TLS 1.2 and 1.3 enabled).

Thanks for this feedback. We will look into it. I know that our test instances also support TLS 1.0 and TLS 1.1.

1 Like

Great news ! I will test it today.
Thanks a lot.

Testing has been quick…

Fehler bei der Überprüfung der Systemkomponente Microsoft .NET Framework 4.5.2 (x86 und x64). Fehlermeldung:
“Die Installation von .NET Framework 4.5.2 wird auf diesem Betriebssystem nicht unterstützt. Wenden Sie sich an den Hersteller der Anwendung.”
Weitere Informationen finden Sie in der Setup-Protokolldatei unter “C:\Users\Romain\AppData\Local\Temp\VSD8052.tmp\install.log”.

My system is a Windows 10 machine with an up to date .net Framework… I do develop an application for 4.7.2 of the .net framework.
A question though, is the software only in German ?
If there is an English version I can help translate it in French if you wish.

Best regards

Hi Romain,

thanks for the feedback. I will discuss your error with the developers. I am kind of suprised about your error message. There seems to be a conflict with .NET 4.5.2. The add-in does not use .NET 4, only .NET 3.5.

On the language: The add-in has an English and German language package (German being the default). For v1.0, there will also be a French translation.

Could you send me the log file referred to in the error message. You find it at C:\Users\Romain\AppData\Local\Temp\VSD8052.tmp\install.log.

Please send to

There is no no release, is there? Project is dead?

Project is not dead. Just delayed. The functionality is there, but there are some usability things we need to improve.

Ok, thanks! Keep going :wink:


I’d like to use this tool, too. But I’m not able to Upload any Attachments to my Cloud. I always get the following Error-Message:
Do you have any Ideas?

Greetings :wink:

Hello. I have the same problem. How did you defeat her?

Project is dead? :slight_smile:

Not dead at all. A version 1.2. of the add-in is almost release ready. Give me a few more days.

This is just great news!
I’ll be looking forward to it.
Thank you for the product

I know we are a little late with an update for Seafile’s Outlook add-in, but I am pretty sure you’ll like it.

You can download the add-in version 1.2.2 here. Please note: The add-in is freeware, but not free software. The source code is not available (for now).

We’ll add some release notes shortly.

Just great! Everything is installed and working!

Tell me how to switch the interface from German to another language?

The add-in should use the language of your Outlook.

The add-in supports Chinese, English, French and German. It defaults to English when you use Outlook in any other language.

I have a different language, but the default and after a restart is still German.

I’m trying to change the language to English, but I don’t understand where and how to do it. Tell me how to do it.Thank you.
ps: I install version 1.2.2 ( & language Outlook Ukrainian