If you unexpectedly quit Outlook while using the Send Anywhere Outlook Add-In, the Send Anywhere Add-In Ribbon may disappear from the menu. If the ribbon disappears, please enable the Send Anywhere Add-In in Options.
Go to File > Option > Add-In.
In the Manage box, change the drop-down menu from ‘COM Add-In’ to ‘Disabled’ and click ‘Go’.
Select ‘Send Anywhere Outlook Add-In’, and then click ‘Enable’. Save your changes and restart Outlook.