In the EAC, navigate to Mail Flow > Rules.
Click the "+" and drop-down to "Apply disclaimers..."
Give the rule a name
Under "apply this rule if..." drop-down to "the recipient is located..." and select "outside the organization"
Click "More options..." then click the "add condition" button
In the drop-down, select "the sender..." then expand and select "is a member of this group"
Find and select the group
In the "Do the following..." section, click the "Enter text..." link and add your disclaimer text and set your fallback action by clicking the "select one" link.
Add an exception if you want
Leave "enforce" selected
Click Save.
You can test the rule by having a member of the group email your external address and check that the disclaimer is applied correctly.
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