This policy setting allows you to prevent Outlook users from adding signatures to e-mails they create, reply to, or forward. ...

This policy setting allows you to prevent Outlook users from adding signatures to e-mails they create, reply to, or forward. If you enable this policy setting, Outlook users cannot manually add signatures to e-mails they create, reply to, or forward, nor will they be able to configure automatic signatures.If you disable or do not configure this policy setting, Outlook 2016 users can add signatures to e-mail messages either manually or automatically.