Sensitive email not surprisingly is filled with love (9)
I believe the answer is:
emotional
'sensitive' is the definition.
(thesaurus)
'email not surprisingly is filled with love' is the wordplay.
'surprisingly' is an anagram indicator.
'is filled with' means one lot of letters goes inside another.
'love' becomes 'o' (love means zero in tennis).
'email'+'not'='emailnot'
'emailnot' anagrammed gives 'emtional'.
'emtional' enclosing 'o' is 'EMOTIONAL'.
(Other definitions for emotional that I've seen before include "gushing" , "Arousing intense feeling" , "Passionate" , "Impassioned - excitable" , "Worked up, upset" .)