domain name system - SPF errors when sending emails

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I setup a mail server on
mail.mydomain.com. I am able to receive email. Problem occurs when i try to send an
email. I have two servers:

• mail.mydomain.com - which
  is on different ip (e.g. 1.1.1.1)


• mydomain.com - which
  has also different ip (0.0.0.0)
  

My SPF record
says:
v=spf1 mx ip4:1.1.1.1 -all

My mx
record for mydomain.com points to
mail.mydomain.com

When i try to send an email
I'm getting following error:

From google:

gmail-smtp-in.l.google.com[2a00:1450:400c:c06::1b] said: 550-5.7.1

[2001:bc8:4400:2b00::32:1f 12] Our system has detected that this
550-5.7.1
message is likely unsolicited mail. To reduce the amount of spam
sent
550-5.7.1 to Gmail, this message has been blocked. Please visit
550-5.7.1
https://support.google.com/mail/?p=UnsolicitedMessageError
550
5.7.1 for more information. m21si1136366wml.110 - gsmtp (in reply to
end
of DATA
command)

From
other server:

host
mx1.seznam.cz[2a02:598:2::42] said: 550 5.7.1
Sender Policy Framework of
`futeq.com' domain denied your IP address. (in
reply to MAIL FROM
command)

For gmail
I also registered and verified my domain using postmaster.google.com

Can anyone point me to the right
direction? am I missing something ?

PS: I
checked and my IP is not
blacklisted

Thanks

Answer

It looks like you forgot to add your IPv6 address to your SPF record, and quite
possibly to your DNS AAAA record for the sending
host.

Of course, mx in
the SPF record covers all IP addresses of the host named in the MX record, so naming the
same IP addresses in the SPF record is
redundant.

To fix the problem, add
your IPv6 address in the DNS AAAA record for your host.