Why does one person cause me this much anxiety when everyone else is fine?

There's this one person in my life, my coworker actually, who just completely wrecks my nervous system every single time I have to deal with them. I can be having a totally fine day and then one email from them shows up and my chest tightens up for hours. I've been trying to figure out why does one person cause me anxiety like this when literally everyone else in my life barely registers, and I still don't get it. It's not even that they're outright mean, it's more this constant low grade dread waiting for the next interaction. Does anyone else deal with this, where just one specific person has that much power over your body and you can't shake it no matter what you do?