mail-from-style

mail-from-style is a variable defined in `sendmail.el'.
Its value is

default

Documentation:
Specifies how "From:" fields look.

If `nil', they contain just the return address like:
king@grassland.com
If `parens', they look like:
king@grassland.com (Elvis Parsley)
If `angles', they look like:
Elvis Parsley

Otherwise, most addresses look like `angles', but they look like
`parens' if `angles' would need quoting and `parens' would not.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20.3 of Emacs.