you dont want his shyness or fear of strangers and men to get out of control, believe me it will if you let it. like i said on your behaviour post, use the rattle bottle if he barks at them and only when he does this, its ok for him to bark when people come to the door (natural guarding instinct).

sounds like he needs to be brought out of his shell. you could try another exercise with him to get used to men.

ask your next door neighbour (the man) to come round, put sunny on his leash, stay calm and collective and ask your neighbour to stand still, let sunny sniff him. you need to tell your neighbour: dont make eye contact with sunny, dont touch him and dont move away when sunny approaches.

when you have hold of the leash you must be calm, assertive and dont even think about sunny introducing himself to your neighbour because if you get nervous then this energy will be passed down to sunny via the leash and he will then get tense ands nervous. you can move with sunny to approach your neighbour.

once sunny has sniffed your male neighbour, he will try to get his attention, but ONLY when he is comfortable with him can he make a fuss of sunny. he could also give him a treat, so that food is the comforter.

this does work, but to make it successful you need to be CALM, ASSERTIVE and RELAXED!