Chiefs here can't ask you for doctor's note. I'm actually blown away that Delta and United chiefs seem to get away with this and that ALPA is somehow OK with it. IMSAFE is your one and only checklist and you're under no obligation to disclose your own personal health or wellbeing information to someone not qualified to assess your personal fitness to fly.

Suppose you get into a big fight with your spouse. Does Delta expect you to fly distraught and violating S and/or E in IMSAFE? What, they want you to get a note from a marriage counselor?

So you get dealt a crappy hand and hit a period where stuff is just not going your way, you've been having a rough patch with your spouse, and then your 12 year old dog dies. What... Delta wants you at work?

I know that I as a pilot am the first person to ascertain whether or not I'm fit to fly. We all sign the document affirming our individual fitness to fly before flying every leg. If I can't sign it for whatever reason, it's either a sick call or a fatigue call. Any undue pressure from the company, and it's an immediate call to the union and the FAA.