Here is my current plan for introducing the RBL support in mod_smtpd, using the existing mod_dnsbl_lookup which I posted earlier. This way of accomplishing the RBL support should not require any code modification to mod_smtpd itself. Nick and Rian, let me know if I should be going about this a different way?
I thought the most modular fashion would be to create a mod_smtpd_rbl that registers the following mod_smtpd hooks: smtpd_run_connect (might deny service to connecting IP, per request_rec) smtpd_run_mail (might deny service to this envelope domain, per loc) These would query whitelists and blacklists, whatever is available. I don't mind whipping up this bridging mod_smtpd_rbl module, but if it seems excessive to introduce a new module for this purpose then the other way of doing this would be to add the RBL supporting code into mod_smtpd itself. Either way it's done, RBLs are still not required and mod_dnsbl_lookup does not have to be present for mod_smtpd to function normally. However, adding a new bridging module has the advantage of leaving mod_smtpd code alone and taking advantage of the hooks interface.
