Given the severity of the issue and privacy concerns it raises, users began calling out Edison Mail for the debacle.
Some said they would never use the app again, while others alleged that if they can see other users' private messages, there is a good chance that their messages/email accounts might be visible to others too.
In a statement to The Verge, Edison Mail said the buggy update reached only a "small percentage" of its user-base and has now been reverted.
"We have quickly rolled back the update. We are contacting the impacted Edison Mail users (limited to a subset of those users who have updated and opened the app in the last 10 hours) to notify them," it added.
We are urgently working to resolve this technical problem in Edison Mail. Yesterday a software update rolled out to a small percent of our users. We have reverted that now and are reaching out to users who have been impacted as fast as we can.