1. It only alerts you ONCE per post. So if you tag a user eighteen times in one post, they only get one alert.
2. If you get an alert about new posts to a thread you are watching, YOU MUST VISIT THE THREAD TO GET ANY MORE ALERTS. It's why the thing even says "Hey dipweed, there may be more new posts after this." It says that
for a reason because it won't alert you to them unless you visit the thread.
3. It won't alert you to a thread you are looking at. EG: If
Sceptic posts something at 3:03 am and
Crooked Bee has the thread open right then and there, enough to be able to say by 3:05 am that "hey, I did not get alerted" then chances are you won't get an alert... because you had already read the thread and seen the alert.
4. If you login, check your alerts. They expire. Saying "well three days ago someone tagged me and I didn't notice it and then today I've got an alert and realised I didn't see the alert I got three days ago" that's you not paying attention.
5. Alerts within quotes, will not alert you unless they're new alerts. EG: If I type
ATyourusername and put that in a quote, I believe that will alert you. BUT if SOMEONE ELSE already did that, and then I just quoted that somebody else, it will not alert you.