Mail servers and Reverse DNS

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Hi,

My local ISP has recently changed the configuration of their mail servers.
They only accept now mails originating from mail servers that can be DNS reversed, i.e mail servers whose domain name can be found using their IP address.
This is for security, to be sure that a mail server that has sent you a message is a valid/known mail server.
This is the reason why some of you have not been able to reach me via my email address : webmaster@pics4fun.com
To solve this issue I have forwarded all incoming emils to this address to another one managed by a Reverse DNS capable mail server.

Has anybody ever experienced this. My local ISP told me that all companies in the world should cnfigure their mail servers like that (most of them are already ok I think)