If an email message has 500 characters, computer would use 7 bits to store that email.
Explanation:
The basic ASCII set uses 7 bits for each character. This gives each character a total of 128 unique symbols. But the extended ASCII character set uses 8 bits. Because of this, there is an additional 128 characters.
The extra character that is present in the 8 bits extended ASCII character has characters from foreign languages and special symbols and characters which can be used to draw images and pictures.