Many large companies in Hong Kong have already used electronic orders. If you use electronic orders, the electronic purchase orders you receive will not be signed and stamped. According to Article 5 and Article 6 1 of the Electronic Transactions Ordinance. 553), the relevant command is still valid. If you confirm that the other party is indeed a subway company, you may wish to wait for the letter of credit to arrive first, and your bank will confirm the authenticity of the letter of credit before you supply it. That will be safe.

Incidentally, in Hong Kong, documents and contracts need not be stamped, but their signatures are enough.