Carried letters from poor Sylvia addressed thus? (5)
I believe the answer is:
toted
'carried' is the definition.
(toting is a kind of carrying)
I don't understand the remainder of the clue.
(Other definitions for toted that I've seen before include "Carried - conveyed" , "Lugged" , "Carried (something heavy)" , "Carried (a gun?)" , "Bore" .)