When you first install Jamroom, the “default” footer for email messages sent from Jamroom looks like:

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Jamroom - the Musicians Website Manager
http://www.jamroom.net
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To remove this, or modify it with a custom message of your own choosing, go into the Admin Menu → Tools → Edit Templates section and choose the “email/email_footer.tpl” template to modify.

Modify that template to suit your own needs and you are all set.