Slack has removed a capability that allowed users to customise external invites with a message after users expressed concerns that the function could subject users to harassment and unwanted messages.

The communications platform has said it “immediately” removed the function on Slack DMs, a new cross-organisational messaging service that only launched yesterday.

Slack DMs was designed as a new feature for Slack Connect, the platform’s external channel sharing feature that provides a secure way of collaborating with teams outside of an organisation, that first launched in June 2020. The DMs feature allowed users to connect with an external user by sending an invite with a bespoke message.

Shortly after its launch, Twitter product developer Menotti Minutillo revealed that the function could be used to send a seemingly unlimited number of malicious messages to external users. The feature would also email a copy of the invite to the target containing the message in full, which appeared to be impossible to block as they originated from a generic Slack address.

Following the initial backlash, Slack has now said that users will be unable to customise messages as part of the invite function.

“After rolling out Slack Connect DMs this morning, we received valuable feedback from our users about how email invitations to use the feature could potentially be used to send abusive or harassing messages,” said Jonathan Prince, Slack’s vice president of communications and policy. “We are taking immediate steps to prevent this kind of abuse, beginning today with the removal of the ability to customise a message when a user invites someone to Slack Connect DMs.

“We made a mistake in this initial roll-out that is inconsistent with our goals for the product and the typical experience of Slack Connect usage. As always, we are grateful to everyone who spoke up, and we are committed to fixing this issue.”

Slack DMs – and Slack Connect – is only available on paid businesses accounts.