You can control which demographic of members will be able to directly inbox you or not. Reduce inbox clutter and annoyances by filtering away messages from certain users to your Message Request folder, which you will receive no notifications of.
To set up your filters, access your Private Messages center, and press the orange button "Filter Messages". A number of options will appear so you can select the relevant options below to filter away these user's messages from your Inbox and redirect them to the Messages Requests page instead. You will also not receive notifications of these filtered messages.
If you want to move a conversation from your Inbox to your Messages Requests, you can enter the private message and press "Ignore Messages".
Contrariwise, you can also move messages from your Messages Requests to your Inbox, by entering the private message on your Message Requests and press "Move to Inbox".