Working with Chinese manufacturers is difficult. Even small stuff that you’d expect to be easy is difficult.
For example, I returned home from the China Import/Export Fair with a ton of ideas of what to import. I have my eye on selling paint pallets. I visited the booth of a Chinese manufacturer, met the team, and came away with a fairly impressive catalog of products to order. They included their business card and contact information.
Today I sent them an email. It’s the same email address in their catalog and on their website. It got rejected for being a bad email address. I thought perhaps I typed it incorrectly. I resent only to have the same result.