> Let's all jump on the bandwagon of another closed-source, proprietary, walled-garden service and hand over all of our private intra-company communications to a private third-party in another country. GREAT IDEA.

Well said, I chuckled. Let me just add something...

If you want a paper trail of anything, use an email you own.

I have a friend who was locked out of a startup's Slack right before he was due to be paid for three months of work. He had been discussing business inside of Slack, and instantly lost access to all of those messages.

Could this have happened if the startup used a private email server, or a private IRC server? Of course. But if they were using more open protocols, he would have at least been able to back up the messages. Slack provides an easy tool for backups to admins, but not for normal team members. Slack provides an API for all users, but team admins can disable the API. Slack also allows team members to connect over IRC and XMPP, if team admins turn on that feature (https://slack.zendesk.com/hc/en-us/articles/201727913-Connec...).

Slack is great, I love using it. Just remember who owns the data. Always use your own personal email if you want to create a papertrail, as my friend found out.