You don't need to use a third-party app for it to work.
Image: Shutterstock / Composition: Louise Matsakis
Update 9/13/17 3:00 PM: Twitter appears to have patched the bug.
Since he was a candidate, President Trump has blocked people on Twitter he doesn't agree with. Late last month, for example, he blocked the Party of Reason and Progress (PORP), a nonprofit committed to "adequately informing the American public regarding modern political issues and policies." Yet, the organization continues to reply to the president, and is receiving more engagement on its tweets than ever.
But how? It turns out a bug in the Twitter mobile app allows users to engage with people who have blocked them easily. Here's how it works.
The Twitter mobile app lets users toggle between multiple accounts. But when you move from one account to another, Twitter doesn't account for whether a user has blocked one of your accounts but not another. You can reply to someone's tweets even though they blocked you, just by first pulling up their tweet on another account.
"I literally just respond to [Trump] (reply) from any other account. Then when I'm writing the reply Twitter has a switch accounts function right at the top," a spokesperson from PORP told me over Twitter DM. "Once I switch, the tweet is still there and I press send."
I experienced the bug with Motherboard's Editor-in-Chief Jason Koebler. First, I had him block me on my normal Twitter account, @lmatsakis. Then I quickly set up a dummy account, @LouiseMatsakis, and signed into it on mobile. While logged into the dummy account, I pulled up one of Jason's most recent tweets. Instead of replying from @LouiseMatsakis though, I just toggled back to @lmatsakis using the button in the right-hand corner.
Jason didn't get a notification when I replied to his tweet, but when he signed out, he could see that I had in fact replied. The reply was also visible to other accounts, but Jason couldn't see it when he was logged in. What that means is that simply by creating an additional dummy account, people who you have chosen to block can engage with your tweets, and other people can see their replies, but you can't.
Trump may have blocked PORP, but he likely doesn't realize that the organization is still replying to his tweets without a problem.
Twitter likely designed its mobile app this way to make it easier for users with multiple accounts to toggle between them, which is great for social media managers or those who have personal and work accounts.
But this bug is also troubling.
The reason the block function exists in the first place is to protect users from abuse. Even though a user doesn't receive notifications when a blocked account interacts with them, it's still disturbing that someone they've chosen to remove from their Twitter profile can engage with their tweets from the same account that was blocked.
I couldn't confirm when the bug began occurring, but I had to update my Twitter app to the latest 7.6 version in order to experience it. I reached out to Twitter for comment and to ask if it will patch the bug. I'll update this story if we hear back.
This isn't the first time a Twitter bug has affected how replies to Trump's Twitter account (and other accounts) function. In February, a glitch was causing replies to the president to become "orphaned" or "disconnected."