If you have SmarterMail 11, 12, or 13.X, you should be able to create an alias called, in our case, "Everyone", and enable XMPP Chat in the alias.
EDIT: 1559 CDT: Since Chat is available only in SmarterMail's Enterprise edition, the "everyone" chat alias shown below can only be created in Enterprise editions of SmarterMail.
You can also use that alias as an e-mail address, with everything sent to the "Everyone@yourdomainname.tld" going to all of your users.
If you mark it "internal only," then it can be accessed only via the webmail interface.
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