"""
Congratulations!

If you are reading this message, it means that your e-mail service provider is
able to receive e-mail from IPv6-only server. Your e-mail is therefore fully
ready for the new internet protocol!

--
DoesNotWork.eu
"""

Grâce au répondeur test@doesnotwork.eu (IPv6 seulement), j'ai pu valider que mon serveur savait envoyer/recevoir du mail en IPv6.

"""
Sep 14 15:47:24 dedibox postfix/smtpd[6960]: connect from www.doesnotwork.eu[2001:1528:132:70::d0e5]
Sep 14 15:47:24 dedibox postfix/smtpd[6960]: Anonymous TLS connection established from www.doesnotwork.eu[2001:1528:132:70::d0e5]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Sep 14 15:47:24 dedibox postfix/smtpd[6960]: 8B605FFB57: client=www.doesnotwork.eu[2001:1528:132:70::d0e5]
Sep 14 15:47:24 dedibox opendkim[809]: 8B605FFB57: s=doesnotwork2015 d=doesnotwork.eu SSL
Sep 14 15:47:24 dedibox postfix/qmgr[26726]: 8B605FFB57: from=test@doesnotwork.eu, size=1793, nrcpt=1 (queue active)
Sep 14 15:47:24 dedibox postfix/smtpd[6960]: disconnect from www.doesnotwork.eu[2001:1528:132:70::d0e5]
Sep 14 15:47:24 dedibox postfix/pipe[6963]: 8B605FFB57: to=********@fralef.me, orig_to=egoijegoijzg@fralef.me, relay=dovecot, delay=0.12, delays=0.07/0/0/0.05, dsn=2.0.0, status=sent (delivered via dovecot service)
"""