My email is working fine this afternoon/evening, yet I've just clicked on a thread I've not opened before to see that someone @'d me at 17:30.
I haven't had the usual email notification for this.
But... looking at that red balloon top right, it looks like an @ notification joined the list of general notifications that people have commented on a thread I'd looked at.
I don't check these - so please tell me this is not the only place @ notifications will show up?! I don't want to look through hundreds of "blah blah posted on rhubarb rhubarb" just in case one of these tedious prompts was actually for me.