iNewsletter can automatically post a news feed item into Facebook, with a link to your newsletter, when you publish a newsletter.
To setup the integration, or change the page associated with your iNewsletter publication:
On the Dashboard for the Publication you want to setup the integration for and go to Settings > Integrations
Next to Facebook click the + icon or the pencil icon to add/edit the integration
In the popup window that appears, login to Facebook with an account that has access to the Facebook page. This might be your personal Facebook account, but once you select the relevant Facebook page we will only have access to the page, and not your account.
Click Save & Close
You can also delete the Facebook integration by clicking the Trash icon.
When you go to publish your next newsletter, you can click the Switch icon next to Share to Facebook to enable publishing to Facebook. When you click the Switch icon, you'll be prompted to add the text that you'd like to appear on the Facebook post.