Slack
Connect Slack in Settings. From then on, react to any message with the memo emoji (📝) and the whole thread is saved as a note in Parley Notes.
Parley Notes can see the channels and messages you can see and saves a thread only when you react. It checks for new reactions regularly and Settings shows when it last did.
Email to Parley Notes
Settings, under Email to Parley, shows a forwarding address that's yours alone. Forward an email to it and it becomes a note: a summary, the decisions and the action items from the thread.
Only mail from your own address is accepted. If a message from another address of yours was refused, Settings shows it and lets you allow that address. You can make a new forwarding address at any time; the old one stops working.
What does it cost?
Notes made from Slack threads and forwarded emails are counted per note, not by minutes: 20 a month on Free, 50 on Plus, with no ceiling on Unlimited.