The post of Russia.
I live in China. On Friday, he sent himself 30+ kg of catalogues from the exhibition from Shanghai to Guangzhou. Specifically asked to send the simplest post of China. Not in a hurry and would like to be cheaper. They said that the package will arrive in 5 days. Today Sunday (2nd day), at 8 a.m., I was awakened by a call from the courier of the postal service. At 9 o’clock in the morning, I had a box of catalogues at home.
This is how email works in "normal" countries.