Owners (and moderators with the applicable permissions) can control the use and creation of hashtags through various means:

• Group hashtag settings

  Group hashtag settings are in the Message Policies panel on the group’s settings page. These settings are:

  • Hashtags Required: Specifies whether messages must have at least one hashtag.
  • Hashtag Permissions: Controls whether group members can create new hashtags by adding them to message subject lines.
• Moderator hashtag permissions

  The setting that allows moderators to create and modify hashtags is Create or Modify Hashtags, which is in the Moderator Permissions panel on a moderator’s member page. See Making a member an owner or moderator. 

• Usage settings on individual hashtags

  When you create a hashtag, you can specify whether it can be used only by moderators by selecting the Use by Mods Only setting. When you select this setting, you can select an additional setting, Replies by Mods Only, so that only moderators can reply to messages that have that hashtag.