Alerting emails stop unexpectedly

Ok, I got some logs of the alerting stuff:

logs.bin.gz (431 KB)

I don’t see any errors though. One thing I noticed is that at 3:14:09 PM an alarm came in that should have been e-mailed out but it says that no addresses could be found. I checked my alert groups and contacts and everything is there in the database, here is my alert group setting that would apply to that alarm:


and the contacts that are assigned to that group are there as well. What should I look for now?