loadplugin Mail::SpamAssassin::Plugin::VBounce [/path/to/VBounce.pm]
The hostnames can be file-glob-style patterns, so "relay*.isp.com" will work. Specifically, "*" and "?" are allowed, but all other metacharacters are not. Regular expressions are not used for security reasons.
Multiple addresses per line, separated by spaces, is OK. Multiple "whitelist_bounce_relays" lines are also OK.