Adds parts to the 'in' and 'at' arrays of the Mail_IMAPv2::$msg property.
Warning: As a method used internally by Mail_IMAPv2, Mail_IMAPv2::_addPart should not be used directly. Its API has the potential of being changed in future releases, should I find a more efficient approach.
| param | int | &$n The offset indice of the field being added to the 'in' or 'at' array. |
| param | int | &$mid message id |
| param | int | &$i The offset indice of the field being referenced in the structure array. |
| param | str | $part One of in|at. Toggles whether fields are added to the 'in' or 'at' array. |
| return | void | |
| access | private | |
| see | Mail_IMAPv2::_scanMultipart | |