Problems with Freenet and DNS PTR record

[HansUnland]

Hello,

Today I got in trouble with Freenet. I tried to send an e-mail to a recipient at freenet.de and got the following:

This is the mail system at host blah-blub.de.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<[email protected]>: host mx.freenet.de[2001:748:100:40::8:110] said:
550-inconsistent or no DNS PTR record for xxxx:xxxx:xxxx:xxxx::xxxx:xxxx (see
RFC 550 1912 2.1) (in reply to RCPT TO command)

That's funny because all other mail-servers accept my DNS config. Just Freenet didn't. So I had a look into Plesk and found the default abbreviation <ipv6> for my PTR record. Which resolved to xxxx:xxxx:xxxx:xxxx:0:0:xxxx:xxxx of the provider config. This was not accepted by Freenet. They obviously accept only the condensed version.

To solve this I replaced the <ipv6> placeholder by hardcoded xxxx:xxxx:xxxx:xxxx::xxxx:xxxx. And this works.

Who does now the mistake? My provider? Plesk? Freenet? Charly Sheen?

Kind Regards
Hans