Sentence:  The Madonna letters, which are interspersed with more personal <WSD>missives</WSD> in this curious epistolary memoir, accumulate into a rap about the downsides of celebrity - the problems of ageing, of invaded privacy, of becoming vain and impetuously adopting children from other continents. 
Meaning of the word marked with <WSD> tags:  A written message; a letter, note or memo.