Facebook announced a policy change this week that will allow Messenger chat bots to send promotional and subscription-based messages to users. However, the new policy also places limits on how and when businesses may contact you.

In an example illustrated by VentureBeat, a travel bot on Facebook Messenger could not previously upsell users on hotels and cars to go along with their plans. Now product placement and native advertising are possible under the new policy. But Facebook also instituted a series of limits to help prevent these bots from spamming users. First of all, users must reach out to business bots in the first place to start an interaction.

“All conversations between businesses and people must be initiated by the person receiving the messages, who can then mute or block the business at any time,” Facebook’s Seth Rosenberg wrote.

Businesses must also respond to users’ messages within a 24-hour period, though they are permitted to send one message after that. Each interaction resets the clock, allowing businesses to “re-engage inactive users.” Facebook also promised to review all bot applications within five days of submission, and recipients must opt into all subscription messaging.

While these rules will help restrict spam on Facebook Messenger, it still seems like the social media giant has opened the floodgate to advertising on a platform that was previously just for you and your friends. Only time will tell if the ads and promotions go too far.