Just went to the website, contrary to what you said,

来源: 2008-04-22 13:40:13 [旧帖] [给我悄悄话] 本文已被阅读:

They don't accept mail service for visa application (authorized service is fine).

They DO accept mail service for travel document service.

http://houston.china-consulate.org/visa/chinese/yj.htm

Maybe they changed the rule recently. But you got the ino from the website, didn't you? Same website as the one above?