[nsp] IP source problem

[Lucas Iglesias]

Hi,

I'm happen to have a customer who has his own IP addresses and needs to do
upload by me, but not download. He has another provider from where he does
the download. Hence, I do not advertise their prefixes. 
Now, I have a provider (lets call him ... verio) who seems to be filtrating
packets based on the IP source (I think with uRPF), which it's ok, but in
this particular case it is a problem for me.
Do you know a simple way to work it out?

I thought in the possibility of advertising my customer prefixes with some
community which makes verio to discard it, but it's too complicated and I'm
not sure it will work (and I really would like not to create a conflict with
his prefixes).

Thanks in advance.
Lucas.