In this window you select message recipients. By rolling down the combobox at the top of the window, you may select either a address book folder or news server. After choosing one, the left window will contain folder contents or subscribed groups on that server. If any of message recipients have more than one e-mail address specified, all available addresses will be shown, with additional being indented. Right window contain all current message recipients. To add recipients, select them from the left window (or click twice to select all) and click the button corresponding to recipient type ("To:", "CC:", "BCC:") or specifying whether that's a group or redirection ("Group:" or "FUT:"). Recipients may be removed by using "Delete" button. You may also use drag and drop to add or remove recipients.
Clicking "OK" will commit changes.