Simplifying even more and just using the Diagnostic email rather than creating a support ticket - I still get the same behavior: sending to a gmail account works, but sending to iCloud results in it going away silently at Apple's end. Sending an email directly from that same outbound account is also accepted by Apple, but the email DOES get delivered.When I manually send the following email, it DOES get delivered.Received: from 192.168.79.254 (SquirrelMail authenticated user support@<REDACTED>) by <REDACTED> with HTTP; Mon, 17 Feb 2014 10 -0600Message-ID: <b87647dd806188363970d91010d3f90e.squirrel@<REDACTED>>Date: Mon, 17 Feb 2014 10 -0600Subject: Test messageFrom: support@<REDACTED>To: <REDACTED>@me.comUser-Agent: SquirrelMail/1.4.20-1.3.17MIME-Version: 1.0Content-Type: text/plain;charset=iso-8859-1Content-Transfer-Encoding: 8bitX-Priority: 3 (Normal)Importance: NormalPlease accept this for delivery - this IS a valid email regardless of whatyou may think, Apple!ScottNow, do we have a good way of getting the raw text of the emails osTicket is sending? It doesn't seem to capture anywhere. Ah, never mind, I'll just set up a "tap" and have it copy to another account.Delivered-To: scott@<REDACTED>Received: by 10.220.162.138 with SMTP id v10csp135380vcx; Mon, 17 Feb 2014 09 -0800 (PST)X-Received: by 10.182.113.195 with SMTP id ja3mr3167400obb.46.1392656979068; Mon, 17 Feb 2014 09 -0800 (PST)Return-Path: <support@<REDACTED>>Received: from mailhost.<REDACTED> (<REDACTED>. ) by mx.google.com with ESMTPS id e6si5390771oen.10.2014.02.17.09.09.38 for <scott@<REDACTED>> (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 17 Feb 2014 09 -0800 (PST)Received-SPF: softfail (google.com: domain of transitioning support@<REDACTED> does not designate <REDACTED> as permitted sender) client-ip=<REDACTED>;Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning support@<REDACTED> does not designate <REDACTED> as permitted sender) smtp.mail=support@<REDACTED>Received: (qmail 11613 invoked by uid 89); 17 Feb 2014 17 -0000Received: by simscan 1.4.0 ppid: 11605, pid: 11608, t: 0.1467s scanners: attach: 1.4.0 clamav: 0.97.3/m/dReceived: from unknown (HELO localhost) (support@<REDACTED>@<REDACTED>) by mailhost.<REDACTED> with ESMTPA; 17 Feb 2014 17 -0000Content-Type: multipart/alternative; boundary="=_cca84295dc0199c97d15c4c1d0787b81"MIME-Version: 1.0From: "<REDACTED> Support" <support@<REDACTED>>To: <REDACTED>@me.comSubject: osTicket test emailDate: Mon, 17 Feb 2014 17 +0000Message-ID: <ycM5kbZEGg6.4-hV-support@<REDACTED>>X-Mailer: osTicket Mailer--=_cca84295dc0199c97d15c4c1d0787b81Content-Transfer-Encoding: base64Content-Type: text/plain; charset=utf-8dGVzdA==--=_cca84295dc0199c97d15c4c1d0787b81Content-Transfer-Encoding: base64Content-Type: text/html; charset=utf-8dGVzdA==--=_cca84295dc0199c97d15c4c1d0787b81--And there we see the problem (or you would if I didn't have to strip out IP addresses and such. The error is that my mail server sits behind a NAT firewall, and the outbound traffic doesn't leave on the same IP address that the INBOUND traffic comes in on (which is what's in the A record for the host). This makes a SPF policy failure. I've updated the SPF records to include that outbound IP address and will test again.Sorry for the fire drill - I will post again if it doesn't resolve, but I'm thinking it will.