- Sign into your respective Office365 Portal (portal.office.com) with your account (this account is most likely work related that includes the appropriate admin rights that will allow you to proceed with the steps below).
- Select ‘Admin’ from the options listed below:
3. Select ‘Admin Centers’ and then ‘Skype for Business’:
4. Select ‘Legacy Portal’:
5. Select ‘Organization’ and then ‘External Communications’. From there, select the appropriate options and include the domains you’d like to Block or Allow.