I need a little guidance on a spam related email rejection our website is having. It is a Wordpress site hosted with WPengine. As far as I'm aware it's using the default PHP mailer.
I've configured an SPF record for our website's domain that allows the WPengine IP's by way of include:wpengine.com. This in turn has it's own IP's and includes that add google SPF's, SendGrid SPF's and so on. There is also a number of other IP's and includes in our record, but despite the fail from http://www.kitterman.com/spf/validate.html, and the warning about too many lookups from MXtoolbox, the SPF is valid.
We're receiving all form submissions from our site (I did add some Exchange message rules to make sure they are delivered into the inboxes rather than junk or clutter), and so are other Exchange email servers our various offices have that use a different email domain. There is one problem office that has a Kerio mail server that is rejecting form submission emails from our website.
I know this because I've setup a "Mail User" on our Exchange server with an external forward to the Kerio mailbox the form submission is intended for.
Form submission emails are from: firstname.lastname@example.org to MailUser@ourdomain.com.au (forwarded to email@example.com). When I do a message trace on our Exchange, I see the following results:
Is this problem mine entirely? Or can I simply ask the administrator of this Kerio mail server to create some whitelist entries for our email domain, the WPengine site and the form submission email subject?