We've recently tightened up the reverse & forward DNS tests applied by our inbound SMTP servers (zuul.ihug.co.nz); sending hosts with mismatched > DNS entries are now likely to have all messages rejected.

Just to note. You are not rejecting them (with SMTP Error Codes), but you are not accepting the connections at all. (Well Answering and then hang up straight away) which will mean SMTP Servers (without RDNS) will just keep trying and trying (Until a undetermined time). (and maybe putting more load on your servers over time) Rejecting the Connection with SMTP Error Codes will make it alot easier for other people todiagnose (as you can give the remote email server a reason for the mail not being accepted). If this is a commercial decision for this way of dong things then its up to Vodafone/IHUG to do it their own way. Also I know a few help desks got a number of calls yesterday about it (and they had contacted IHUG helpdesk before this and they (IHUG Helpdesk) knew nothing about this implementation of your email server./ Thanks Craig Whitmore Talking for Myself