SAN FRANCISCO – Words of warning for the 300 million active users of Twitter: there will be spam. In a move bringing sweeping change to one of its defining settings, the social media giant has announced that direct messaging, a feature allowing users to write messages to another user’s private mailbox (i.e., outside of the public eye), will no longer be limited strictly to users who follow one another, i.e., opt to routinely receive a user’s maximum 140-character public posts in their accounts’ ongoing newsfeeds.

Under the change, users would not be immediately subject to direct private messages from the entire Twitter community, but only after toggling a privacy setting that would allow them to opt to receive messages from users who they do not presently follow. This will be a point of relief for the site’s multitude of celebrity users, who could potentially have their private mailboxes flooded by messages not simply from their present mass user followings (e.g., Barack Obama’s 58.2 million, Justin Beiber’s 62.9 million, or Lady Gaga’s 45.8 million), but rather by anyone willing to undergo Twitter’s easy username/password/e-mail address signup process.

While the option to opt out of receiving messages from any and all users may prove simple for high-profile individuals, this decision will be nowhere near as simple a matter for high-profile companies, many of whom maintain Twitter accounts to facilitate their interfacing publicly with their customer base. Dan Swartz, senior vice president of digital marketing, media and analytics at Upshot Agency opined in a recent article in Adweek :

“Brands must expand Twitter private messaging into a continuing infrastructure of social platforms [that] they need to actively manage in order to seamlessly connect with consumers,” Swartz said. “If a brand decides not to activate their private DM [direct message] functionality, it sends a bad signal to consumers that they are not interested in what they have to say.”

The result for widely followed brands choosing to opt in (in the spirit of welcoming the sentiments of their clientele) could potentially be waves of messages from users choosing to contact them abusively in a setting where, by contrast to Twitter’s previous configuration, their comments would not be visible to the general public.

For the everyday Twitter user with a modest following, opting in for universal direct messaging will leave them as potential targets for brands to send them notices, promotional offers and advertisements. The major beneficiary in this brand-to-consumer messaging corner of the new configuration will inevitably be Twitter itself, which can potentially generate untold sums of revenue by charging brands to privately solicit these users en masse.

Time will tell how each party in the celebrity-corporate brand-everyday user triangle will take to the new direct messaging option into their everyday usage of the service. Regardless, it can be said that the public’s relationship with the platform will be met with inevitable change.