one of my co-workers emails keep disappearing off my email inbox

I had issues two weeks ago with my emails being full. They added more space and one of my coworkers emails started to go into my Spam folder. Then today they showed up in my inbox and after I read them they disappeared completly. Right after that every email since he started with us last year disappeared off my inbox. I need customer support to call me to fix this. [edited phone# and email from public]