Hello
I have multiple hosts on same server with one IP-address
domain1.com domain2.com domain3.com

My linode rDNS is set to domain1.com

SPF for domain1.com is set to v=spf1 ip4:xxx.xxx.xxx.xxx ?all (xxx.xxx.xxx.xxx is the ipv4 address of my linode
SPF for domain2.com is set to v=spf1 mx a:domain2.com a:domain1.com -all
SPF for domain3.com is set to v=spf1 mx a:domain2.com a:domain1.com -all

I also set opendkim but when email is sent i have the following worning:
warning: connect to Milter service inet:localhost:2029: Connection refused

My problems:
1 - for dkim should I add in iptables a rule allowing 2029 for localhost? How should this rule look like?
2 - for domain1.com when send mail to yahoo, the header of the mail say that SPF pass and referes to linode ip-address, while sending same mail to gmail SPF fails and referes to linode IPV6 address. I don't know anything about ipv6, can it be removed? Do I need it ?
3 - while checking SPF on http://tools.bevhost.com/spf/ I see that rDNS is ok for domain1.com but fails for domain2 and domain3. Is that important? How can I coorect this situation?

BR

Found problem for
1) - the port in /etc/postfix/main.cf was different from one in opendkim.cnf. I set same port and no more warning. Now I got this message :

opendkim[11526]: 7E5B23461: no signing table match for 'admin@domain3.com'    
opendkim[11526]: 7E5B23461: no signature data

Do I need to add each mail in some conf file? like admin@domain1.com sales@domain1.com etc??

I had a similar problem sending email to Google Apps email accounts. My solution is posted here: viewtopic.php?f=11&t=10596#p61351
(Hint: I had to disable ipv6)

Here's what I have for my DNS TXT record for SPF in the "Value" field (notice the quotes):

"v=spf1 a ~all"

Here's what I have for my DNS TXT record for DKIM in the "Name" field:

mail._domainkey

Here's what I have for my DNS TXT record for DKIM in the "Value" field:

v=DKIM; k=rsa; p=[here's the key...]

Feel free to add more info (e.g. logs or conf) and I could try to help, if possible. Good luck!