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Mail from an IPv6 host to an IPv4 host

2004-08-27 04:24:00
If an IPv6-only host sends mail to an IPv4-only host, then receiver does not
see the IPv6 client address but an IPv4 address that is not correlated to
the IPv6 address. So the receiver does not know from where the mail came.
This is a similar problem as with forwarding, except that no SRS (sender
rewriting scheme) can be done.

And the sender does not know what IPv4 address the receiver will see. So
they cannot have "ip4" in their SPF record.

This means that all mail from an IPv6-only host to an IPv4-only host (doing
SPF) will be rejected unless the sender implements SES (signed envelope
senders).

Please correct me if I am wrong.

Roger


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