mail order 
noun [mass noun]
The sale and ordering of goods by post, generally involving selection from a catalogue: available by mail order only [as modifier]: a mail-order catalogue...
- This year the tubers will be offered in the centre's mail order catalogue.
- Many of the forcing jars available today at florist shops or via mail-order catalogues are reproductions of famous designs from the Victorian era or earlier.
- Bulbs are widely available this month in retail nurseries and mail-order catalogs.