It may be old, and you may think it's a little corny, but according to a Mailjet study, it's exactly the type of tactic you need to get open rates shooting up. Actually, more to the point, it's the type of tactic that gets open rates in Britain. FOMO accounted for a 39% leap in interaction with email marketing campaigns. It's a similar story in Spain but not in France, where FOMO leads to a 9% drop in interaction. In the United States, it makes little difference.
If you're wondering what type of subject gets Brits the most engaged, it turns out it's humour or laughing at someone else's mistakes. And just in case you were wondering, nudity or suggestive headlines have exactly the opposite effect. One can imagine, at the risk of mixing acronyms, that this would put an email in the NSFW (Not Safe For Work) category and that would apply for home opening too.
So if you have been deploying subject headlines designed to illicit a FOMO and it has not had any noticeable effect in the U.S., don't beat yourself up. It's the Brits and the Spanish who love to find out what they would otherwise be missing out on. But try it with the French at your peril.