Thanks! Linen is secretly email in disguise. We have played around with syncing with email clients which would let you manage all your messages and notifications from one client.
As someone who has officially given up on having any semblance of keeping up with the never ending fire house of totally unmanageable slack threads, channels, DMs etc, especially since Slacks update last year, I would sell my left Kidney to just have one big list of things I need to look at at reply to/dismiss.