hunting up people by Owls

[literature_Caro]

No: HPFGUIDX 135361

Hi all!

I have wondered why nobody (neither the MOM nor anybody else) ever
tried to get hold of anybody by sending him/her an owl. Harry always
was able to send Sirius letters by owl though he did not know about
his whereabouts. So an owl can find you even then.
If I was is search of a person I would send him/her an owl with a
little note (lte's say: "Got ya in the end!") and follow the bird. As
long as there was no fidelius charm on the residence you should be
able to find the one you are searching.
Why did the MOM never use this way trying to find out where Sirius
hid? Or even now this could be used to find out where Voldemort is
having his headquarters. Has anyone an idea?

Caro