Send emails to Slack – Slack Help Center

You can get a forwarding email address to send email messages to yourself in Slack (via Slackbot!). From your desktop, click your workspace name in the top left.Choose Preferences from the menu.Select Messages & Media.Scroll down to click Get a Forwarding Address. Click Copy to save it to your clipboard.Paste the Slack-generated address as a new forwarding address in your email application.

Source: Send emails to Slack – Slack Help Center