James Martin/CNET

Twitter is expanding its popular direct message feature to allow users to receive messages from other users regardless if they follow each other. The move is part of its ongoing effort to try to boost user growth as pressure from Wall Street investors continues.

Twitter said Monday its direct message system, which allows users to communicate privately, used to require each user be "following" one another, effectively having made a connection beforehand. Now, Twitter said, the direct messages will operate for anyone who chooses to opt in to the feature.

The feature could be particularly beneficial for large companies and celebrities, who will now be able to respond to people who send them messages without having to establish a connection beforehand.

Twitter had tested this feature in the past, making it available to a portion of its users in 2013. But Twitter didn't push the effort further, until now.

Users can now turn on a setting that enables them to receive direct messages from anyone. And on mobile devices running Apple's iOS or Google's Android operating system, users will see a direct message button on profiles.

Twitter also now allows users you follow to direct message you, whether they follow you or not.

These refinements, Twitter said, will make direct messaging faster and easier because people will be able to more simply communicate. The changes are rolling out worldwide Monday.

"We continue to invest in our private channel to lay the foundation for a powerful and engaging messaging experience," Twitter said in a blog post Monday.

Of course, Twitter isn't the only company that sees value in private messaging. The entire social-networking industry appears to be orienting itself around these types of services.

Facebook recently made it possible for developers to send images, videos and other items through its Messenger communication service, which counts 800 million users. The social-networking giant also bought WhatsApp, a text-messaging-like service that has more than 700 million users, for $19 billion.

Other companies including Snapchat, Line and WeChat have been growing rapidly.

For Twitter, direct messaging is more than just a feature. The change comes after the company last week redesigned its home page in the United States to attract new users without having to sign in. In January, the company launched new group direct messaging and 30-second videos where users can shoot, edit and post their own videos from within the Twitter app.

Twitter has been trying to convince Wall Street that it has a larger audience than just the monthly active users it publishes about. The company is also trying to increase the number of active users. During its fourth-quarter earnings report in February, Twitter said around 288 million people actively use the service monthly. Wall Street had been hoping for about 295 million such users.

The social network is focusing on creating features to attract both passive and active users to use Twitter more frequently. It recently released Periscope, an app that lets people stream live video.

Twitter has also made it easier for media companies to include tweets in their stories and broadcasts, creating curated lists of suggested feeds for new users.

The changes will be available to users on most devices, including those on the iOS and Android operating systems.