Select Hyperlink Prefix
Use the Select Hyperlink Prefix dialog box to select the types of hyperlinks that you want to block, send a warning message, or allow by selecting (to block or send a warning message) or clearing (to allow) the check boxes for their extensions from the categories under Hyperlink prefixes. Click the arrow to expand a category and view all of the hyperlink prefixes for that category. If you want to select all of the hyperlink prefixes for a category, select the category name.
If you do not see a hyperlink prefix that you want to select listed in Hyperlink prefixes, type the extension in the text box under Add new hyperlink prefixes to the list, and then click Add.
After you have added all of the hyperlink prefixes that you want to the Selected hyperlink prefixes list, click OK.
For details about the different procedures that you can perform by using the Skype for Business Server Control Panel, see Manage Skype for Business Server 2015.