This happens periodically and I have never been able to figure it out even after many years. Finally deciding to ask the web.
I have a domain with WordPress on it, on my own hosting account at Hostgator. On that domain I have plugins such as WordFence which occasionally send me emails about things. These emails are sent to my gmail.com address. The email address on the Hostgator account is also the gmail address. My iCloud address (@me.com) is not associated with the domain, hosting account, or plugins in any way.
On occasion I get rejection emails from iCloud, as if I have been sending spam or something from my iCloud address. Here is an example that just came (personal info redacted):
The response from the remote server was: 550 5.7.1 [CS01] Message
rejected due to local policy. Please visit
https://support.apple.com/en-us/HT204137Reporting-MTA: dns; googlemail.com Received-From-MTA: dns;
my_username@gator3035.hostgator.com Arrival-Date: Mon, 09 Dec 2019
14:34:31 -0800 (PST) X-Original-Message-ID:
<773b12e625f3a1a11b8f5a98d6dfa2bc@my_domain.com>Final-Recipient: rfc822; my_address@me.com Action: failed Status:
5.7.1 Remote-MTA: dns; mx4.mail.icloud.com. (17.172.34.67, the server for the domain me.com.) Diagnostic-Code: smtp; 550 5.7.1 [CS01]
Message rejected due to local policy. Please visit
https://support.apple.com/en-us/HT204137 Last-Attempt-Date: Mon, 09
Dec 2019 14:34:33 -0800 (PST)From: WordPress Subject: Wordfence activity
for December 9, 2019 on my_domain.com Date: December 9, 2019 at
2:34:28 PM PST To: my_address@gmail.com
Why is iCloud even involved here, in any way? The email in question was sent by Wordfence, to my gmail address. The only time iCloud comes into play at all is when I retrieve emails since I'm using Mail.app. But why would that have anything to do with this? I don't get it. Any input is appreciated.
EDIT: Adding the complete headers here:
Mail Delivery Subsystem Delivery
Status Notification (Failure) To: my_address+caf_=my_address.com@gmail.com
Auto-Submitted: auto-replied Arc-Seal: i=1; a=rsa-sha256;
t=1575930873; cv=none; d=google.com; s=arc-20160816;
b=Mmp9Br3lNM3rDahSJ/zFi4WVcvzlovXH3SHbSoJ4tofdOIV9nR+efYJ/RTSeTHoVib
C+VLYICot2FhZJa7NISPtUlrfRO6M7PnSLLqee+bpz/DpPc0bRhExE9qKmr9JTBjzcjx
1P/+tYZY1K2XAK7KVmxsF3a+lnsiajzW/XsiqGBefABfCzT+WbpHNNopKHAfnrHqJT2r
VQAnsBPobfO2+r5w21b9xNa2+uaWnGwDjONGr37P+VmBT2NS2krPDQFJVgsMsjurhJdA
D9xwf/Oqi0pilAXYvMTywoG8h1g5RC9UluTa61nlymRZQ5kHP5/1YD5F1BFDCX9UteVr
bV2w== <773b12e625f3a1a11b8f5a98d6dfa2bc@my_domain.com> X-Received:
by 2002:a0c:9304:: with SMTP id d4mr25612477qvd.12.1575930873794;
Mon, 09 Dec 2019 14:34:33 -0800 (PST) X-Received: by
2002:a05:6214:50f:: with SMTP id v15mr16843999qvw.42.1575930873697;
Mon, 09 Dec 2019 14:34:33 -0800 (PST) X-Gm-Message-State:
APjAAAU8bHrG50c6T4Mm5hJBfhUQwEiSCsl9zod3OkhNB8ls+8czmBj1
DJiXv/FVRpgDeELkiWIj+j8/lOOXLkKlJjWGYBNCtA== Return-Path: <>
Return-Path: <> Arc-Authentication-Results: i=1; mx.google.com;
dkim=pass header.i=@googlemail.com header.s=20161025
header.b=BZLI4Xp0; spf=pass (google.com: best guess record for domain
of postmaster@mail-sor-f69.google.com designates 209.85.220.69 as
permitted sender) smtp.helo=mail-sor-f69.google.com; dmarc=pass
(p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=googlemail.com
X-Google-Smtp-Source:
APXvYqzuASmjpUzQH5oRbGlMi6/AslW4bxLHFBzgmoCneaDkZnf3DXmt0gH4zcxLCrd16wwBz2K2QgrTDI6dC8v74rdt04GHQls3+rE=
Authentication-Results: mx.google.com; dkim=pass
header.i=@googlemail.com header.s=20161025 header.b=BZLI4Xp0; spf=pass
(google.com: best guess record for domain of
postmaster@mail-sor-f69.google.com designates 209.85.220.69 as
permitted sender) smtp.helo=mail-sor-f69.google.com; dmarc=pass
(p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=googlemail.com
X-Failed-Recipients: my_address@me.com Arc-Message-Signature: i=1;
a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
h=in-reply-to:references:subject:from:date:message-id:auto-submitted
:to:dkim-signature; bh=+vVumkeSjV1UdpDo3N/fd36LuEEOvN9i2NfWLJL56oI=;
b=zBAX3npJdEzzzOqVQsmTCE4eG4Uy9HIA/FsPVPRRI2J4Ky+tEwuOAf+p82qsJTA4DE
G/5+uRPwRsJsGG8PntsLbLHfw+1W32jkRS5aBrnxiLS3lt475rO0vL88KB7C2Jke2Hpk
Lf8RRR8aT4AMfniCjpcaWxdvl20gTjZLxZwlkUthGZQ+yfUM2o1PtH2Snkds4fJ9uD2a
0uRXr4eN1P4893ngD9T50u87FperOjaLjmzTx2u33WwRMHkhVAHvxnbY1i0voFbCQ3e5
IG55BP8rwZgHZID2tORiQwUVVKXzOyZqtrgNuXh4niHZwz61uWVFrrRXqqqjzQR90gr2
QOnQ== Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=googlemail.com; s=20161025;
h=to:auto-submitted:message-id:date:from:subject:references
:in-reply-to; bh=+vVumkeSjV1UdpDo3N/fd36LuEEOvN9i2NfWLJL56oI=;
b=BZLI4Xp0BVaDs0q46vQVBhybkV1YFZktAsRaUvBE/nA11yGB95ypLPFmXHI8oNPr/I
1mOfI8yGH0iwZQk76vH0vrcyuPHCdN0BFBVm74wZkE/SgqG5n7F/m0SWJH5JwdcSGhbh
vWX45oDIB47fVnRGfAqcYJ8W1B/mws+epy2wMnUmsA0ryVwAdZvXHDK9M8t50p0ug+yE
wFarOVydCBAgBC7igOaK7WLbXT5Zbh8S7DUdFSulcid+cGu07D/8zUByfOM2MivrRCCM
dI9MAVnhZ4qGEwr0DmV2rK8SuhEsPreoHSSd8W1G0WFxcGKW2DSTI5fCQrDEBfytR48K
Veyw== <5deecbf9.1c69fb81.4763e.1333.GMR@mx.google.com>
<773b12e625f3a1a11b8f5a98d6dfa2bc@my_domain.com>
X-Google-Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20161025;
h=x-gm-message-state:to:auto-submitted:message-id:date:from:subject
:references:in-reply-to;
bh=+vVumkeSjV1UdpDo3N/fd36LuEEOvN9i2NfWLJL56oI=;
b=gOgOeh84ppQ43d9/8nNcBZL6XlyWUfyUmZqrlRJ1avyV6v5NBPn4mX/yCNRNY51l8y
s3U+Kwisej15JhEivmeVu8bRjnrPVFc/yS6wMsysjBu+/CSnuLsN89mpcW8hR1QfYSRF
YvmkfvyldbogDHcX4oJ0Pc7+CQEgdcSZ1WGOwzZrvsnc6pAijg6oVP8Bzh7pK5nsoJVq
rpOiZrbz4Ff7ziNJxzVXesbS4ld9Lcm32AEv8Er5eeUHLxEsfD04IfROpZeXgdjIQDPN
P/saIlV+p1r8wycZtURmNJnWbvGBWvBVDatFn+i6SkOXorDVfsqpx58rQabVfjyd1arH
KA5A== Content-Type: multipart/report;
boundary="000000000000eac82a05994cff10"; report-type=delivery-status
Received-Spf: pass (google.com: best guess record for domain of
postmaster@mail-sor-f69.google.com designates 209.85.220.69 as
permitted sender) client-ip=209.85.220.69; Delivered-To:
my_address+caf_=my_address=me.com@gmail.com Received: by
2002:ac8:7593:0:0:0:0:0 with SMTP id s19csp4779624qtq; Mon, 9 Dec 2019
14:34:33 -0800 (PST) Received: from mail-sor-f69.google.com
(mail-sor-f69.google.com. [209.85.220.69]) by mx.google.com with SMTPS
id 61sor679175qva.7.2019.12.09.14.34.33 for
(Google Transport Security);
Mon, 09 Dec 2019 14:34:33 -0800 (PST) Received: by
2002:a05:6214:50f:: with SMTP id v15mr15815744qvw.42; Mon, 09 Dec 2019
14:34:33 -0800 (PST)
Best Answer
From the information given in your answer, it seems that you have setup some sort of forward or filtered forward in Gmail that targets your me.com address.
This can be seen in that you have "my_address+caf_=my_address=me.com@gmail.com" listed. Gmail uses this way of mangling the actual return address to include "+caf_" and the target address with the @ substituted by a =, when it is forwarding mail like this.