Getting started

How to get started, Part 8: Mail links instead of attachments

This is the eighth post in a series meant to get you up to speed. You’ll learn how to send emails that contain ownCloud links instead of attachments - it is safer and supports large files.

By Dirk Stascheit

ownCloud a guide on getting started

All posts on Getting started:

1. How to personalize your account
2. How to use the Web App
3. How to use the Desktop App
4. How to use the Mobile App
4a. Special features on iPhone and iPad
5. How to create Public Links
6. How to create Public Upload Folders
7. How to install the Appliance
8. Mail links instead of attachments

Mail links instead of attachments

Emails are great. They enable universal communication with pretty much everyone on earth that is online.

Mail attachments on the other hand aren’t so great. They duplicate every file, or worse, and thereby are a substantial burden for organizations’ mail servers. Also, they are the number one attack vector for digital crime. That is why state-of-the-art security protocols in high-risk work environments now discourage or even outright ban attachments. So, time to think of a better way.

How to avoid attachments

A much more secure practice is to include links to files or folders in ownCloud instead of attaching the files outright. It saves on storage space and keeps the file under your organizations’ control. Think about it: If the email gets into the hands of an unauthorized party, an attached file is automatically compromised.

A file that is located in your organizations’ ownCloud, on the other hand, is much more secure. Not only can you delete it if things go south, you can also set a password and an expiration period. If your ownCloud includes an Antivirus Scanner and a File Firewall, those security layers also protect malware from making the rounds.

Last but not least, using a file link provider enables you to send files of any size. You’re practically only limited by the available storage space in your ownCloud.

There are two ways to do this: You can manually create a public link and enter it in your email. This is handy if the file you want to send is already located in your ownCloud. Alternatively, there are so-called link provider plugins for Outlook and Thunderbird. While the Outlook Plugin only works on Windows, Thunderbird is also available for Macs and most common Linux Distros.

Replacing attachments in Thunderbird

*cloud is an extension to the open source eMail Client Thunderbird, created by Mozilla, the Foundation that also develops the Firefox Browser. Like the ownCloud Outlook Add-In, *cloud activates itself if and when you attach a file.

First, you’ll need to download the extension ( Then, open your Thunderbird’s preferences tab and select ‘attachments’.

Send links to ownCloud instead of clunky attachments.

Here’s how to configure the Thunderbird extension

Click on ‘Add *cloud’ and add your server URL, username and password. Instead of entering a password, you can also use an app token, it’s more secure that way. It means if your computer gets stolen, you do not have to change your password but just need to invalidate the app token. For this, open your ownCloud URL in a browser, log into the web app and open the settings page.

Under security, scroll down to the bottom. There, you can create a new app token by entering a name, e.g. thunderbird001. If need be, you can also just delete the token on this page to end any access to your account obtained through this token. Then, copy the freshly created token, return to the Thunderbird attachment settings page and enter it instead of your password.

On this page, you can also specify from which file size Thunderbird should suggest uploading an attachment to your ownCloud instead of attaching it natively. Set it to zero to suggest uploading regardless of file size. The default is 5 MB.

Don’t forget to have a look at the advanced options. *cloud uploads your selected file into your ownCloud. By default, the uploaded files are located in a folder called mail-attachments in your ownCloud’s home directory. Here, you can set another directory, if you want.

Also in the advanced options area, you can configure an expiry period (the default is seven days), and whether to password protect your uploads. You can choose whether to use the same password for every uploaded file onto randomly create a specific password for every attachment you create.

Then, click save. If your settings are correct, the extension will show you that your configuration was successful, alongside information about the ownCloud version and the free space left in your account.

Now you can close your preferences tab. In Thunderbird, click the write button to create a new email. Add an attachment. Notice the notification seal informing you that ‘This is a large file. It might be better to use file link instead’. Click ‘Link’ to convert the attachment to a file upload, and then you can hit ‘send’.

Replacing attachments in Outlook

The ownCloud Outlook Add-In, developed and sold by our partner EpikShare, is a file link provider for Microsoft Outlook. It empowers users to convert attachments to ownCloud links, on the fly, right within Outlook.

After downloading (get it here, you have to connect the ownCloud Outlook Add-In to your ownCloud by entering your organization’s ownCloud URL and your account details.

Then, just create a fresh email draft, attach any file to it and hit send, the file will be safely stored in your ownCloud, detached from your email and replaced by a link to the same file in your ownCloud. You can (and are strongly encouraged to) use a password or an expiry date or both for sending a file.

Here’s a neat video walkthrough of the process:

And there you have it – how to send files without actually sending files, because it’s the safer way.

Dirk Stascheit

October 7, 2020

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