What's happen if mail server down?

What's happen if mail server down?

Downing of mail server can not do anything with it, it may caused by many reasons, such as the hardware is not work, connecting to the server with ISP is not work, the error of software of the server. It's similar to a computer that you always use, one day it probably doesn't work because of problems of power supply, motherboard, video card, Ram.

Normally, the mail server might be downed every time like the computer.

The effect when the mail server was downed. 

1. Can not send / receive messages.
2. Miss a big opportunity to make business contacts.
3. Out of credibility in the business.
4. Affect mental of employees.
5. Inconvenient contact.