Location header rewrite

[nguyen.tho]

How do I go about rewriting the Location header in a response?
I have setup nginx as a reverse proxy to a web mail server.  Everything
run good if data is self contain on that server.  When an email have
links to different servers in its environment, it sends the Locations
header with the uri to it.  How do I go about search and replace these
value.

I have tried the proxy_redirect but it doesn't work.
I have looked at both the header and headers_more module but it doesn't
provide a search and replace function.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,219582,219582#msg-219582