I investigated SPF because gmail was returning some of my emails with the code:
Error transferring to gmail-smtp-in.l.google.COM; SMTP Protocol Returned a Permanent Error 550 5.7.1 our Bulk Email Senders Guidelines
Gmail's Bulk Email Senders Guidelines are here: http://www.google.com/mail/help/bulk_mail.html
One solution for my email to be not returned was to add a SPF record to my domain record.
How does SPF affect your Lotus Notes Mail Server?
If you send email to other services you may be required to have SPF set up on your domain record.
If you receive lotsof email you might like to set up SPF protocol on your server.
A list of SPF Implementations are here: http://new.openspf.org/Implementations
The only Lotus Notes server implementation I have found is: http://www.policypatrol.com .
What do I put in my Domain Record for SPF?
There is a wizard to create a SPF record here: http://www.openspf.org/wizard.html
The text is put into the host's TXT section.
Example text:
v=spf1 a mx mx:swapgroups.com mx:durablesoftwareltd.com mx:ssilicon.com mx:2silicon.com mx:adfos.com mx:si-mation.com mx:swapstick.com mx:notesninjas.com ?all
How do I test my SPF hosts setting?
You can test the setting here: http://www.kitterman.com/spf/validate.html?
You can send an email to: check-auth@verifier.port25.com
More test places are listed here: http://new.openspf.org/FAQ/Testing_and_validating
SPF Problems:
One problem I have found is that if you list too many mx: domains you receive the error:
Too many DNS lookups
The 10 lookup limit is a MUST in RFC 4408 apparently. This is to prevent Denial of Service attacks.