Sina.com’s microblog service Weibo.com has fully closed its open platform private messaging interface to prevent third-party applications from sending private messages to Weibo users.

This move aims to solve some of the private messaging harassment problems users have complained about in recent months. However, it also tightens Sina’s reins over how advertising messages are sent to users of its service. By closing the door to outside senders, Sina now controls full access to any advertiser or organization wishing to send messages to its users.

On the old version of Weibo’s platform, which is similar to Twitter, some third-party applications sent business marketing messages or special media spam information via the private message system, which caused many problems for users. To solve the problem, their new version’s interface will not fully open the private message interface.

According to a representative from Sina microblog open platform quoted in local media, the former private messaging interface did not open to all third-party applications either and only those that met certain standards could apply to use it. However, after the full closure of the private message interface, no application is allowed to use it now.

The company added that the closure of the open platform private message interface will not affect the normal use of ordinary users and they can still send private messages to each other.