Is this still true Armo? This was the problem with the old version but I don't understand why this hasn't been addressed yet (it's the very definition of what monitoring network nodes is, and is how practically all other tools work).
This is literally as easy to do as when an email is sent, the program should either amend to a file or registry entry with a monitor identifier (a simple way to tell which alert fired the email) and a value (1-red 2-green 3-black). When the program thinks it should sent another email, check to see what the last state was by reading that file/registry entry and see if the actual condition is changing or not. If for some reason you like the way it works now (which spams folks false up/downs all night long) you could always put a checkbox on each monitor called "enforce state change only alerts" which would turn this feature off/on for that specific monitor.
This is actually why we didn't buy this product when it went to pay version, because without this easily added feature, it's too unreliable for us to use as our primary alert utility. I've been using the free version with a really long interval for RED only alerting, just incase our primary monitoring tool fails.
Seriously though, I've been programming for nearly 35 years and this would be one of the easiest features for your developers to add. Without it though, just not enterprise ready. Which is a shame, Solarwinds and most of the big boys out there are simply insane on pricing for this sort of thing. I just re-installed version 2 just to see what you guys have added since last year and was immediately disappointed that this problem hasn't been addressed.
On a positive note, I really think you guys got nearly everything else right on this program. The new GUI looks great.