Sending file

The IT security team of the University of Vienna has compiled a list of practical tips for students and employees on how to send large or sensitive files or files to a large group of people securely.

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ACOnet FileSender

Use cases

In the following cases, the ZID recommends using ACOnet FileSender to send files securely.

Sending a large file

E-mail systems and most messaging services (such as WhatsApp, iMessage, Signal) have a limit on the size of files that can be sent. This is usually only a few MB in size. With the ACOnet FileSender, you can send files up to 250 GB in size and send invitations to external people to receive files from them. You can find more information about the limits in the ACOnet FileSender under Help.

With special software (such as 7-Zip) you can split a large file into several smaller files. This can be helpful if you are using a slow or unstable internet connection.

Sending a file with sensitive content

With ACOnet FileSender you can encrypt files containing sensitive information end-to-end. In this case, only the person sending the file has the password to decrypt the file. Send the download link to the file and the password via 2 different channels, for example the download link via e-mail and the password via text message or phone call. If one of the two pieces of information falls into the wrong hands, the file is still protected from unauthorised access.

Without encryption, third parties can open the download link and download the file, for example if the link is passed on or the communication (for example the e-mail notification) is read.

Sending to a large group of people

You can use ACOnet FileSender to send files to as many people as you like. To do this, read the user guides Sending file with the option Get a link instead of sending to recipients. You can share the download link to the file in different ways (e.g. presentation slide, meeting chat). Please note the validity date of the download link.


Files are available via the ACOnet FileSender for a maximum of 15 days.

Alternatively, you can also share files via the u:cloud, especially if:

  • you want the file to be available for longer than 15 days
  • you want to edit the file together
  • you need the option for comments in Office documents