I work in a foreign company. Generally, everyone is very busy at work. I don't have time to read a polite letter, which contains many adjectives and long sentences, which will make readers lose patience. I think it is good to be simple and clear.

Dear Sir/Madam,

I am writing this email to ask if you have an agent in China. As far as we know, your company is one of the major companies in XX industry. We are willing to cooperate with you and become your friends. Please let us know if we have the honor.

We look forward to your reply.

Best wishes,

XXXX