spf=pass (google.com: domain of catchall@mydomain.com designates ????:????:????:????::???? as permitted sender) smtp.mailfrom=catchall@mydomain.com
Return-Path: <catchall@mydomain.com>
Received: from mail-yb0-x22e.google.com (mail-yb0-x22e.google.com. [????:????:????:????::????])
        by mx.google.com with ESMTPS id y66si667532ybc.27.2017.06.15.00.51.39
        for <test@otherdomain.com>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Thu, 15 Jun 2017 00:51:39 -0700 (PDT)
Received-SPF: pass (google.com: domain of catchall@mydomain.com designates ????:????:????:????::???? as permitted sender) client-ip=????:????:????:????::????;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@mydomain-com.20150623.gappssmtp.com header.b=aFbgG/RI;
       spf=pass (google.com: domain of catchall@mydomain.com designates ????:????:????:????::???? as permitted sender) smtp.mailfrom=catchall@mydomain.com
...
From: Admin <unknownname@mydomain.com>
To: Test <test@othermain.com>