Specify whether to restrict the set of e-mail servers that can route mail directly to this server farm. This setting can ...

Specify whether to restrict the set of e-mail servers that can route mail directly to this server farm. This setting can help ensure the authenticity of e-mail stored in SharePoint sites. Enter one IP address per line in the format "11.22.33.44" or "11.22.33.44, 255.255.0.0".