If the Google Apps anecdote is true, it's likely to be a design flaw in their anti-spam systems - think of the number of spammers who could register domains, associate them with a $5 google apps account, and spam millions of Gmail recipients. If you think about the kind of metrics/outcomes the Gmail anti-spam team uses to measure success, it's hard to imagine a scenario where that would be good for them.
What this looks like to me is a reputation problem with one or more domains, either in your headers or your message content.
From a domain reputation perspective, you don't generally need to 'build' reputation in the same way you often do with IP reputation; rather, Gmail tends to tag domains with negative reputation only when they've observed unusually bad behavior associated with the domain.
Sometimes this can happen due to domain forgery or spoofing. Sometimes it's because a sender is doing overly aggressive email marketing. Sometimes it's just because your domain shows up in someone else's bulk email.
With full authentication, spoofing is unlikely; I also don't see any indication you're doing email marketing here, and your IP 88.198.5.136 doesn't appear to generate much more than a trickle of volume. So - perhaps the latter? Has anyone included a link to one of your blog posts in an email newsletter, for example?
It would also be helpful to see full headers and content; it's great you're doing SPF/DKIM/DMARC, but they're not going to prevent all issues - there might be something elsewhere in your message that gives us a better idea where the problem is.
Finally, keep in mind that anti-spam systems are highly dynamic, and results can change - sometimes in as little as a few minutes - based on the latest data feeding into the system. If you're lucky, you might see this resolve on its own fairly quickly.
>anti-spam systems are highly dynamic, and results can change - sometimes in as little as a few minutes - based on the latest data feeding into the system. If you're lucky, you might see this resolve on its own fairly quickly.
and
>this will most likely be fixed tomorrow morning as a result of this thread.
I didn't take Boris' comment at face value. I took it to be a joke.
I think he understands that it's different. He was humorously implying that the issue will be resolved by a Gmail person seeing the thread, as opposed to some AI spam filtering.
Google does read threads about them, but seldom comments. When Google Local first came out, I mentioned on Slashdot that most big companies tended not to "claim their page" on Google Local, and that Google hadn't even claimed their own page on Google Local. Google claimed their own Google Local page within hours.
If its true, its likely it's only a small part of the score but who knows, it might be enough to push my domain into the good graces of gmails spam filters.
I doubt you'd get away with doing it for a domain sending legitimate mail, or at least not for very long.
After 2+ years of hosting my domain myself, it doesn't seem possible to build up enough reputation with them personally.