You can use the "Filter" function on the [Customers] page to find out customers with line tags or Current Customer Form tags. For customers who use LINE, the system will automatically label them with "LINE".

On the [Customer] page, click [More Criteria] at the top to expand the menu, click the [tags] column in the menu, and search [LINE] or [Current Customer Form]:


Then you can see a list of customers who use "LINE@", and customers will have a "LINE@" tag on them.