Hi, thought I'd mention this, and this seems like the best place to put it.
I just used the forum's recover password facility to get my gmail email address linked account back. The process involved being sent two emails. The first one ended up in my spam folder (unusual), and I told gmail that it wasn't spam. So did the second, which I don't think I've ever seen before - false positives seem very rare with gmail, and to get one after I've already approved a previous email from the same address seems very odd.
There's nothing particularly spamy about the emails themselves. They contain links of course, but nothing you'd think would trigger a spam filter more than any similar email.
The 'from' however is reported as: Xenonauts Forums chris@xenonauts.com via weplayciv.com
The via bit links to an explanation here:
https://support.google.com/mail/answer/1311182?hl=en-GB&ctx=mail
At a guess this is probably the money shot:
"Gmail checks whether emails are correctly authenticated. If your messages are sent by a bulk mailing vendor or by third-party affiliates, please publish an SPF record that includes the IPs of the vendor or affiliates which send your messages and sign your messages with a DKIM signature that is associated with your domain."
Which is a load of acronyms to me that are vaguely familiar from hearing the guy who deals with our mailserver at work moan about them
Just thought I'd point it out - if gmail are spam filtering you it's probably happening quite a bit.