Thank you for reaching out about this! The Social Posts feature was retired and is no longer available. You can, however, continue to use the Social Share feature to share your email campaigns. I'm sorry there's not a workaround to creating a Facebook post without first sending your email campaign. An option might be to schedule/send your email campaign to an email list that contains just your own email address in order to utilize Social Share.
Nichelle M Community & Social Media Support
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