Hello list refers to the list of people you have to or want to say "hello" to on a daily basis, especially relevant for students in university buildings, or coworkers in a workplace. Some people might decide to put you on their hello lists, even if they aren't on yours. Typically, reciprocity is expected.

“打招呼列表”指的是你平日里碰见时必须或想打招呼的人，那些经常穿梭于教学大楼的学生，或单位里的职员，都会有这样一张“打招呼列表”。某些人也许会把你放在他们的“打招呼列表”里，尽管他们并不在你的列表上（意思是他们会主动和你打招呼，而你不会）。不过，通常他们也期待你以后会主动和他们打招呼。

Example:

Dropping someone from your hello list to just a nod when you pass him or her might be considered a snub by the other person.

把某人从“打招呼列表”里移除，碰到时只是点点头，可能会被对方视作怠慢。