Add an option to set a SO as cost estimate only and create a workflow that will change the Cost Estimate only once it has been sent by mail.
Hide button Confirm Cost Estimate when Cost estimate only is active
Add a filter to see all Cost Estimates Only
Filter tree view to show Done cost estimate only in Cost Estimates
Move user_id on view and rename it Business Unit Officer
Rename project_id to Project code
Add Currency related on pricelist_id
Rearange fields in view
Restore fields attributes in view
Add field remark on LO