The Cc field inherits from StructuredField and handles the Cc: header field in the email.
Sending cc to a mail message will instantiate a Mail::Field object that has a CcField as its field type. This includes all Mail::CommonAddress module instance metods.
Only one Cc field can appear in a header, though it can have multiple addresses and groups of addresses.
mail = Mail.new mail.cc = 'Mikel Lindsaar <mikel@test.lindsaar.net>, ada@test.lindsaar.net' mail.cc #=> ['mikel@test.lindsaar.net', 'ada@test.lindsaar.net'] mail[:cc] #=> '#<Mail::Field:0x180e5e8 @field=#<Mail::CcField:0x180e1c4 mail['cc'] #=> '#<Mail::Field:0x180e5e8 @field=#<Mail::CcField:0x180e1c4 mail['Cc'] #=> '#<Mail::Field:0x180e5e8 @field=#<Mail::CcField:0x180e1c4 mail[:cc].encoded #=> 'Cc: Mikel Lindsaar <mikel@test.lindsaar.net>, ada@test.lindsaar.net\r\n' mail[:cc].decoded #=> 'Mikel Lindsaar <mikel@test.lindsaar.net>, ada@test.lindsaar.net' mail[:cc].addresses #=> ['mikel@test.lindsaar.net', 'ada@test.lindsaar.net'] mail[:cc].formatted #=> ['Mikel Lindsaar <mikel@test.lindsaar.net>', 'ada@test.lindsaar.net']