When are users messaged with DM automation?

We message users once ever: when they DM you or reply to a post.

Does DM automation work with Reddit chat?

Postpone only replies to DMs, not to chat messages. Reddit does not provide third parties like Postpone the ability to interact with Reddit chat, which makes it impossible for us to support chat automation at this time.

Who is messaged from DM automation?

Postpone will message users starting when you enable your first automation template. Postpone won't message subreddit moderators and Reddit admins.