File sharing is a supported feature for Mio Universal Channels on Slack, Microsoft Teams, and Webex Teams. We also support and encourage the sharing of links for files stored on Google Drive, Dropbox, Box, etc.

Why does a file shared in Slack or Webex Teams show up as a link in Microsoft Teams?

Mio Universal Channels uses adaptive cards in Microsoft Teams when impersonating messages from Slack and Webex Teams. These cards are limited to holding files under 1 MB or with an image resolution of 1000x1000. If the file is larger than either of those, it must be posted as a link instead.

Microsoft currently does not have an API that allows us to post file attachments on behalf of the Mio bot. However, Microsoft regularly announces new developments in Graph APIs and are focused on maturing those interfaces, so we will be ready to improve the experience as soon as we're able to.

Are the generated links for shared files secure?

Files that are shared in a universal channel are stored in a private, non-traversable secure storage. Only the Mio application can access and serve the files via a unique, complex URL. The link is not discoverable until it is posted by Mio to Microsoft Teams.

The link expires after a certain amount of time. Once the file expires, if the file is requested again, we fetch it from the source.

We use complex URLs that are hosted by the app from which Teams can retrieve the file. We can’t point Teams directly to Slack due to permissions so we act as an intermediary. We supply Teams with our unique endpoint so the file can be fetched by Teams.

To learn more about security at Mio, check out our white papers:

What's next?

We have plans on our roadmap to improve and enhance control for the Pro and Enterprise plans in the future. This includes having the option to "turn off" file sharing in a universal channel by removing that scope from the bot.

Install Mio Universal Channels today to start chatting with external contacts within minutes.

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