My team's use case is pretty generic: when someone posts a link, we want to enhance that post by inserting some relevant markup underneath post. We would like to be able to write our own outgoing web hooks for this purpose and would like them to work both in public channels and private groups. Some examples (although there are many more):

- Someone links to an NBA game (http://www.nba.com/games/20170201/MINCLE) and a box score is automatically inserted after the link
- Someone links to a Github issue (https://github.com/CraigPhillips/aws-ebs-snapshot-cleanup/issues/1) and a summary of the issue shows up after the link
- Someone links to an Amazon product page (https://www.amazon.com/Stainless-Chopsticks-Lightweight-Camping-Neoprene/dp/B01CDJ9KLK) and a preview image and description is added after the link.

It looks like this feature was under consideration, judging by this ticket: https://mattermost.atlassian.net/browse/PLT-1655. It appears to have been closed with the intention of enabling this kind of thing through bot accounts.

I understand the concerns about this compromising the privacy of private channels but those concerns seem like something that a server/channel admin should be able to decide on themselves. As the original poster said, a per group-level of toggle would be great but an all or nothing, server-level switch would meet our needs.

Personally, our team doesn't need any kind of notification that outgoing webhooks are enabled and potentially sending your information out but if that's something important to other people we wouldn't mind it. The notification examples in the linked ticket seem fine to me although I could also see going a lot less subtle if it's a real concern like: https://s3-us-west-2.amazonaws.com/fe-share/images/mattermost-hooks-in-private-warning.png - with an option for a user to dismiss.