We've got American & British colleagues who are planning a business trip for meetings in our Shanghai office for a couple of days and also possibly meetings with Clients as well.

I understand that we need a Letter of Invitation in support of a Visa Application.

1) Will a letter from our Shanghai office suffice or must it be a letter from Client?
2) Must the Letter be an Original? Or would a coloured scanned Letter of the original suffice?

Thank you