# File lib/mail/field.rb, line 70
    def initialize(name, value = nil, charset = 'utf-8')
      case
      when name =~ /:/                  # Field.new("field-name: field data")
        charset = value unless value.blank?
        name, value = split(name)
        create_field(name, value, charset)
      when name !~ /:/ && value.blank?  # Field.new("field-name")
        create_field(name, nil, charset)
      else                              # Field.new("field-name", "value")
        create_field(name, value, charset)
      end
      return self
    end