Well let's see, I registered on your wiki with a Gmail address and I got:
Received: by 10.27.93.139 with SMTP id r133csp841052wlb;
Sun, 26 Jul 2015 03:26:54 -0700 (PDT)
X-Received: by 10.140.42.98 with SMTP id b89mr33012264qga.78.1437906414160;
Sun, 26 Jul 2015 03:26:54 -0700 (PDT)
Return-Path: <...@piratemc.com>
Received: from mail-qg0-f46.google.com (mail-qg0-f46.google.com. [209.85.192.46])
by mx.google.com with ESMTPS id e92si16674252qga.85.2015.07.26.03.26.53
for <...@gmail.com>
(version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
Sun, 26 Jul 2015 03:26:54 -0700 (PDT)
Received-SPF: pass (google.com: domain of ...@piratemc.com designates 209.85.192.46 as permitted sender) client-ip=209.85.192.46;
Authentication-Results: mx.google.com;
spf=pass (google.com: domain of ...@piratemc.com designates 209.85.192.46 as permitted sender) smtp.mail=...@piratemc.com
Received: by mail-qg0-f46.google.com with SMTP id u79so34137324qge.1
for <...@gmail.com>; Sun, 26 Jul 2015 03:26:53 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20130820;
h=x-gm-message-state:from:date:message-id:mime-version:content-type
:content-transfer-encoding:subject:to;
bh=7DxPJYAXIahN7eGPo8i8huPCfaouA1fa5IpmfMY+DK8=;
b=PyiE5THk6ai9Rfy3H1nIkJFiyiiGJjMGqq2hlq4mcKdtHnQlcJDJ/JnF0RSI2DI/ms
VwZ2fbz10/u+skgQ0DzgQC0qbIWRsc5vEF40TWUcvGH5Lu6PKT3JPfaP8t42rwfpeF/M
RRFwjju7wUM9FjqZaydpgWEtLzwV6EPdOyqvvznVM8rbzAknBC+w2fAs830pd4XT/8a4
fjD9G5wJW3CLElqS+O9Qp8qfbRKH6/WOvaBRV44N1f5o5ubBGXHGji84Ljz0Q5noaTdU
tSFukefPKxtd4PT77I1YeKCaC/Y3mZor/AENfjkVh6RdfyuWhfJZa5lZ61xt8FYdJ7MW
CPaQ==
X-Gm-Message-State: ALoCoQkcwsKyr6WXZQn3SKqAaeIoxryylA6QNULlonPL5AYRSaOIoOjCiZz0nxy6w+kxWUm5xHPN
X-Received: by 10.141.28.139 with SMTP id f133mr13915894qhe.30.1437906413389;
Sun, 26 Jul 2015 03:26:53 -0700 (PDT)
Return-Path: <...@piratemc.com>
Received: from localhost (panda.abstractdns.com. [205.251.130.98])
by smtp.gmail.com with ESMTPSA id q19sm7062455qha.32.2015.07.26.03.26.51
for <...@gmail.com>
(version=TLSv1 cipher=RC4-SHA bits=128/128);
Sun, 26 Jul 2015 03:26:51 -0700 (PDT)
From: PirateCraft <...@piratemc.com>
Return-Path: ...@piratemc.com
Date: Sun, 26 Jul 2015 10:26:50 +0000
DKIM and SPF pass, IPs and domains don't seem blocked at https://www.spamhaus.org/lookup/ : that's pretty good!
Maybe you just needed more time to get out of some blacklist after you fixed the configuration?
Alternatively, there might be some content-based spam filter. You should check said spam filter and report back to them that they are blocking legitimate content.