The Return-Path is currently set to bounce@wp.com, which may be contributing to emails getting marked as spam for some recipients. Relevant headers from one such email:
Received-SPF: Neutral (zoho.com: xx.xxx.xx.xxx is neither permitted nor denied by domain of bounce@wp.com ) client-ip: xx.xxx.xx.xxx
Authentication-Results: mx.zohomail.com;
spf=neutral (zoho.com: xx.xxx.xx.xxx is neither permitted nor denied by domain of wp.com) smtp.mailfrom=bounce@wp.com
Return-Path: <bounce@wp.com>
...
Date: Fri, 20 Oct 2017 12:20:46 +0000
From: WordPress <wordpress@wordcamp.org>
Reply-To: support@wordcamp.org
This same issue has come up before (1, 2), and it appears that the Return-Path was changed at that time, so perhaps it was somehow reverted at a later date?
cc @stankea