Several of you have reported issues with alerts right now. You may be experiencing getting alerts for resources long after they have spawned or just not getting alerts at all. The service that checks for the alerts and sends out the emails seems to be a bit backed up right now. I'll be working to help get it caught up, but this will likely take a couple days and some alerts for resources that spawns over the last 5 days might not go out.
You may want to keep a closer eye on the resources spawning in your galaxy until I get the alerts system caught up.
-ioscode