How to prevent that sbs 2011 communicate with the internet on ipv6 protocol for smtp

Hallo,

I want to sent a email to Gmail account i receive everytime this error message from mx.google.

--[------ Oorspronkelijk bericht --------]
Van: Microsoft Outlook <MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@kantoorgevaert.be>
Datum: 08-01-2016 08:16 (GMT+01:00)
Aan: Microsoft Outlook <MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@kantoorgevaert.be>
Onderwerp: Onbestelbaar: Fw: Verlichting b-terrein
mx.google.com heeft uw bericht voor de volgende e-mailadressen geweigerd:
Johan Van den Bossche (bossiesabrina@gmail.com)
mx.google.com gaf deze fout:
[2a02:a018:203:1800:b41a:da6d:522f:666] Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review https://support.google.com/mail/?p=ipv6_authentication_error for more information. ko8si163220171wjb.26 - gsmtp ]

My provider (proximus) don't support for the moment Ipv6 PTR adressing
is their another solution ?

Thanks,

Lode