Each message has a header which consists of several header fields.
All header fields can be divided into two types: address fields and non-address fields. Address fields such as "To:", "From:" etc. contain information about originator and destination addresses. Field of this type contains MailAddressList.
Use AddMailAddressList, DeleteMailAddressList and GetMailAddressList methods to manipulate such fields. Use AddField, DeleteField, GetField and SetField methods to manipulate non-address fields.