When I'm in charge of social media, I'll enforce a 14-day cooling-off period, and for every day of that period, there'll be a message you have to click that reads 'are you absolutely sure you want to send this in n days?'
Any failure to click 'yes' to every message in the 14-day period will cancel the posting. At the final point of posting, they have to agree to endure a short but vicious electric shock. Only after they've survived that will the message appear.