Can this be an explanation of why many “eastern” mail servers do not have a valid PTR record? This is what came up on RFCI-discuss last week:
“If they want to set a PTR for an IP,they must ask to their ISP.Ok ISP can do that,but they require addtional money.It’s about 25 USD per month for a PTR record for each IP.”
Boy do I hate such business practices*. Some months ago I was forced to stop using FEATURE(`require_rdns’) because I had users complaining about communications with servers located at Middle Eastern countries.
Yeah I know, it is long time due for another custom hack dealing with exceptions.
[*] – Led by internet tourists no doubt.
Managing organized complexity 
Unfortunately, same situation here.. Even though the use of FEATURE(`require_rdns`) could be turned off per user in our network, it only lasted for about a week..
I envy so much others who enforce it’s usage and then stick to this decision!