我检查了太多主题，答案也测试了太多东西！但找不到我的问题的解决方案。我是新手用户，可能对某些答案不太理解。我需要尽快解决这个问题，所以我创建了这个主题，希望找到一个清晰（且易于操作）的答案。
我使用 Virtualmin 作为邮件和 Web 服务器。IP
更改为12.345.678.910
域，更改为mydomain.com
原始区域：
; mydomain.com Dumped Thu Sep 26 07:48:41 2019
;
mydomain.com. 86400 IN SOA ns1.he.net. hostmaster.he.net. (
2019092609 ;serial
86400 ;refresh
7200 ;retry
3600000 ;expire
86400 ) ;minimum
mydomain.com. 3600 IN A 12.345.678.910
mydomain.com. 3600 IN NS ns1.he.net.
mydomain.com. 3600 IN NS ns2.he.net.
mydomain.com. 3600 IN MX 10 mail.mydomain.com.
mydomain.com. 3600 IN TXT "v=spf1 mx a ip4:12.345.678.910/32 -all"
_dmarc.mydomain.com. 300 IN TXT "v=DMARC1; pct=100; p=quarantine; adkim=r; aspf=r"
mail.mydomain.com. 3600 IN A 12.345.678.910
www.mydomain.com. 3600 IN A 12.345.678.910
key._domainkey.mydomain.com. 3600 IN TXT ( "v=DKIM1; h=sha256; k=rsa; p=key )
PTR已设置为mail.mydomain.com
SMTP正常工作（使用 thunderbird 发送消息）
https://mxtoolbox.com并检查所有错误已解决。
https://www.mail-tester.com获得 10/10。
https://appmaildev.com/en/dkim一切通过
original mail in gmail
SPF：通过 IP 12.345.678.910 了解更多
DKIM：通过域名 mydomain.com 了解更多
DMARC：通过 了解更多
Delivered-To: [email protected]
Received: by 2002:a1c:a891:0:0:0:0:0 with SMTP id r139csp1564644wme;
Thu, 26 Sep 2019 08:18:21 -0700 (PDT)
X-Google-Smtp-Source: APXvYqygH8PjdOkQW09orM3iSqTtZcC2oQjhwtP88nMdhMiznjGZzhG+Qp0OpKSakQ2gXTVkEUrJ
X-Received: by 2002:a1c:e008:: with SMTP id x8mr3369089wmg.85.1569511101641;
Thu, 26 Sep 2019 08:18:21 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1569511101; cv=none;
d=google.com; s=arc-20160816;
keys
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
keys
ARC-Authentication-Results: i=1; mx.google.com;
dkim=pass [email protected] header.s=2019 header.b=N+Lzr0yv;
spf=pass (google.com: domain of [email protected] designates 12.345.678.910 as permitted sender) [email protected];
dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=mydomain.com
Return-Path: <[email protected]>
Received: from mydomain.com (mail.mydomain.com. [12.345.678.910])
by mx.google.com with ESMTPS id p8si1812998wrt.517.2019.09.26.08.18.21
for <[email protected]>
(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
Thu, 26 Sep 2019 08:18:21 -0700 (PDT)
Received-SPF: pass (google.com: domain of [email protected] designates 12.345.678.910 as permitted sender) client-ip=12.345.678.910;
Authentication-Results: mx.google.com;
dkim=pass [email protected] header.s=2019 header.b=N+Lzr0yv;
spf=pass (google.com: domain of [email protected] designates 12.345.678.910 as permitted sender) [email protected];
dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=mydomain.com
Received: from [192.168.1.105] (unknown [151.243.44.80]) by mydomain.com (Postfix) with ESMTPSA id D5017A3F53 for <[email protected]>; Thu, 26 Sep 2019 16:18:19 +0100 (BST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mydomain.com; keys.
zgdZicdOospHQ==
To: [email protected]
From: Franck <[email protected]>
Subject: fact to read
Message-ID: <[email protected]>
Date: Thu, 26 Sep 2019 18:48:15 +0330
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Venus was once habitable until a mysterious event occurred. Venus likely
sustained stable temperatures and hosted liquid water for billions of
years until something triggered the release of carbon dioxide from rocks
on the planet about 700 million years ago.
等/主机：
127.0.0.1 localhost
127.0.1.1 lubuntu
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
##12.345.678.910 mydomain.com mydomain
12.345.678.910 mail.mydomain.com mail
等/主机名：
mail.mydomain.com
dig -x 12.345.678.910 +短
mail.mydomain.com.