You can send a post as email by clicking on the caret (the arrow pointing down) next to Post and picking "Send as email".
To use this feature, you need to have the Moderate other Members permission enabled.
In the Send post as email window you can edit the Subject Line, which starts as "New thread in" followed by the channel name, and see how many Members the email will reach before you send it. Turn on Schedule send to publish and email the post at a set date and time. Otherwise it goes out as soon as you click Post & Email.
Who receives the email
Everyone who can see the channel and has Unread DMs & mentions emails switched on in their notification settings. Ignore notification preferences emails everyone in the channel regardless of their settings, so keep it for critical updates or legally required communications.
Every email ends with an "Unsubscribe or manage email preferences" link, which opens the member's notification settings.
What the email includes
The email carries the post's text and any images in it. Wide images shrink to fit the email and smaller ones show at their actual size. Link previews, file attachments, polls and voice notes aren't included, so put any link you want members to click in the text itself.
Frequently Asked Questions
Why did members get two emails from one post? If the post also mentions @Everyone or a Group, members who haven't seen it within 4 hours get a separate mention email. Leave the mention off when you use Post & Email.
Can I send posts as email on a recurring schedule? No. Each post is emailed once, either right away or at the time you schedule.
How can I test the email first? Send it in a private channel where you're the only member.
Should I use a separate channel for email announcements? It helps. A dedicated channel keeps the posts you email in one place where members can reply and react.