The expanded message composing window that appears when you click the Format icon has more neat tricks up its sleeve.
If you want to make a conversation really stand out, you can turn it into an announcement. In the expanded message formatting window, click the New conversation drop-down at the top left and select Announcement. A field appears where you can type a large headline for your post and optionally include a background image or colored background to make it stand out even more.
Tip: By default, everyone in a channel can reply to conversations, but you might not want that for an announcement. If you click the Everyone can reply drop-down at the top of the message composing window, you can select You and moderators can reply to limit responses to only these people.
If you want your conversation to appear in more than one channel, select Post in multiple channels, click the Select channels button, and on the panel that opens, check the boxes next to the channels you want to post your conversation to.
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