Mahlzeit is a German salutation. It is the short form of a more formal salutation, "Gesegnete Mahlzeit" (archaic term, de: Blessed mealtime). The salutation is commonly used without connection to food or eating in Northern Germany, and this usage, corresponding to something like "hello, everyone" or "I'm off, folks", is becoming more and more widespread in informal settings, such as between office co-workers.
Mahlzeit is a German greeting. It's an abbreviated version of "Gesegnete Mahlzeit" (an old term, de: Blessed mealtime). The greeting is frequently used without any connection to food or eating in Northern Germany, and its usage, similar to "hello everyone" or "I'm off folks," is becoming increasingly common in casual settings like between office colleagues.