电子邮件在 SPF 等之后仍然落入垃圾邮件；为什么？

Question

我已经使用phpmailer自动化了PHP中电子邮件的发送：

$mail->isSMTP();

$mail->SMTPAuth = true;

$mail->Host = $host; // verified with my host 
$mail->Port = 465;

$mail->Username = '[email protected]'; // verified with my host 
$mail->Password = 'mypassword'; // verified with my host 

$mail->SMTPSecure = 'ssl';

$mail->SMTPAutoTLS = true;
$mail->setFrom( '[email protected]', 'This is the Header of the E-Mail' );
$mail->addAddress( '[email protected]', '' );
$mail->isHTML( true );
$mail->Subject = 'This is the Subject of the E-Mail';
$mail->CharSet = 'UTF-8';
$mail->Body = 'HTML Content of the E-Mail';
$mail->send();
$mail->SmtpClose();

首先，许多通过此脚本发送的电子邮件落入了我的客户邮件中。我与主机签了检查，他们帮助我添加了一个SPF记录：

• 类型：TXT
• TTL：300
• 值：“ V = SPF1 REDIRECT = shared_host_mail_server”

这使非SPAM交付率大大提高了很多，但对于Gmail来说，尤其是重要的，部分仍然掉入垃圾邮件中。掉入电子邮件垃圾邮件中的电子邮件源的一个示例是：

Delivered-To: [email protected]
Received: by 2002:a17:906:f12:0:0:0:0 with SMTP id secret;
        Mon, 21 Mar 2022 06:58:32 -0700 (PDT)
X-Google-Smtp-Source: ABdhPJz6F29tChwOYHMaPAlJC0D9QTnj/JMhktHDZEuWjHBWU7x/ZdnkZS7MccoMwSxrMjrZec73
X-Received: by 2002:a5d:4ad2:0:b0:203:d56d:9c82 with SMTP id secret;
        Mon, 21 Mar 2022 06:58:30 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1647871110; cv=none;
        d=google.com; s=arc-20160816;
        b=K3FgBLtaiFZEsUAPiR2dBpquBEVEKZ2A82PhG+nCN7I7NRTxE8KDueotg3pndOeoQQ
         IaCxIO8uYvkka1BmdSz8RuL0H/+OuXh+UMTpuy5tnhteTy3IR5Ub8vfl2eCl5AsCUj1R
         ZLkysapUMphblFlZnSz4JObVz0jgN8P4uAE39ObN1YVpLZ9bT//BXuVjyYbKuHyhDUoP
         AnZ+cjey7I4dyuvaaUWyrIMC7xEnLratGSN4mtIBWhEuWrMokXZtnbVZMHtNh+W7d5d1
         HGmWzWdnWftGZJFI8e2fnNSRosRE0pwzblCNAkGd+PmJHOEDlq5pmaLla1I9yZpxZa3z
         dx4w==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=content-transfer-encoding:mime-version:message-id:subject:from:to
         :date;
        bh=NCbhFSalLdDA2HAK57ps0Gy6VG+hTVJz6G8PW0XPkpo=;
        b=TuIDSDjGMJOISTWTkb8iaOA1qJ3QYFLU6adhuG2kbyzpICBc0EC5MNvkGDWcEH9znp
         UjYJ0Uug/79c6ZSzLaXuv3THIwuO7MJTuM5r7YXTbFvGnwNlO/Qc1xO/bo63rIN1ZS8y
         aKRtpzjO0hMqjxlbltnZPcNice0DqZZcX0BlaU8kkgKFGw96vpBj9A0ZZbAyvmK2Lyws
         oGYdKUmcOhosxXIxM8AAu1JVtM0bI2EncDo5UvwBIXVitvgcmORTfS1u3RBsKakk9tXI
         bBCer6hxpjjn+hRxMOsdjqFdLa0EIIxnuW/z05Yh4CYSPBi1RZM0q/hWCMPvjDqBRFY5
         8vVQ==
ARC-Authentication-Results: i=1; mx.google.com;
       spf=pass (google.com: domain of [email protected] designates 2a00:d70:0:e::313 as permitted sender) [email protected]
Return-Path: <[email protected]>
Received: from host_out_mail_server (host_out_mail_server. [2a00:d70:0:e::313])
        by mx.google.com with ESMTPS id secret
        for <[email protected]>
        (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
        Mon, 21 Mar 2022 06:58:30 -0700 (PDT)
Received-SPF: pass (google.com: domain of [email protected] designates secret_ip as permitted sender) client-ip=secret_ip;
Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of [email protected] designates [email protected] as permitted sender) [email protected]
Received: from [10.0.2.46] (helo=host_mail_server) by host_out_mail_server with esmtps
  (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2 (FreeBSD)) (envelope-from <[email protected]>) id 1nWIYH-0000QW-8D for [email protected]; Mon, 21 Mar 2022 14:58:29 +0100
Received: from other_host_server ([2a00:d70:0:b::2:10] helo=example.com) by host_mail_server with esmtpa (Exim 4.95 (FreeBSD)) (envelope-from <[email protected]>) id 1nWIYG-00010j-7w for [email protected]; Mon, 21 Mar 2022 14:58:29 +0100
X-Authenticated-Sender-Id: [email protected]
Date: Mon, 21 Mar 2022 13:58:28 +0000
To: [email protected]
From: Werbe - Anfrage <[email protected]>
Subject: Bekanntmachung
Message-ID: <[email protected]>
X-Mailer: PHPMailer 6.5.0 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="b1_ciluFWHutVghcyNH2SHrnSBIhFM0AuGhsYu8JefeYks"
Content-Transfer-Encoding: 8bit

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<html lang=3D"de" xmlns=3D"http://www.w3.org/1999/xhtml" xmlns:o=3D"urn:sch=
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<head>
  <meta charset=3D"UTF-8">
  <meta name=3D"viewport" content=3D"width=3Ddevice-width,initial-scale=3D1=
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  <meta name=3D"x-apple-disable-message-reformatting">
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    table,
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    /* RESET STYLES */
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    table {
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      .max-width {
        max-width: 100% !important;
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      .mobile-wrapper {
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    div[style*=3D"margin: 16px 0;"] {
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<body style=3D"margin: 0 !important; padding: 0; !important; word-spacing: =
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<div style=3D"display: none; font-size: 1px; color: #fefefe; line-height: 1=
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max-width: 0px; opacity: 0; overflow: hidden;">
    This is the text of the preheader
</div>

<table role=3D"presentation" border=3D"0" cellpadding=3D"0" cellspacing=3D"=
0" width=3D"100%" bgcolor=3D"#d3d3d3" style=3D"background: #d3d3d3;">
    <tr>
        <td align=3D"center" valign=3D"top" width=3D"100%" style=3D"padding=
: 0;">

            <!--[if (gte mso 9)|(IE)]>
            <table role=3D"presentation" align=3D"center" border=3D"0" cell=
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            <tr>
            <td align=3D"center" valign=3D"top" width=3D"600">
            <![endif]-->

            <table role=3D"presentation" align=3D"center" border=3D"0" cell=
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px solid #000000; border-right: 1px solid #000000; border-bottom: 1px solid=
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        <img src=3D"https://example.com/mail_visual.png" wi=
dth=3D"600" border=3D"0" alt=3D"" style=3D"display: block; width: 100%; hei=
ght:auto;" class=3D"img-max"/>
    </td>
</tr>

                <tr>
    <td align=3D"left" valign=3D"top" bgcolor=3D"#ffffff" style=3D"backgrou=
nd: #ffffff; padding: 15px 30px 30px 30px; font-family: Open Sans, Helvetic=
a, Arial, sans-serif; border-left: 1px solid #000000; border-right: 1px sol=
id #000000;">
        <h4 style=3D"font-family: Open Sans, Helvetica, Arial, sans-serif; =
font-size: 17px; line-height: 23px; color: #000000;">Salutation</h4>
        <p style=3D"color: #000000; font-family: Open Sans, Helvetica, Aria=
l, sans-serif; font-size: 16px; line-height: 22px; margin: 0;">Sample Context</p>
    </td>
</tr>

                <tr>
    <td align=3D"center" valign=3D"top" bgcolor=3D"#13aff0" style=3D"backgr=
ound: #13aff0; padding: 10px 30px; font-family: Open Sans, Helvetica, Arial=
, sans-serif; border-left: 1px solid #000000; border-right: 1px solid #0000=
00; border-top: 1px solid #000000;">

      <h5 style=3D"font-family: Open Sans, Helvetica, Arial, sans-serif; fo=
nt-size: 16px; line-height: 24px; color: #ffffff; margin:0 0 5px 0;">Domai=
n</h5>
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@example.com" target=3D"_blank" style=3D"text-decoration: none; color: #fff=
fff; font-family: Open Sans, Helvetica, Arial, sans-serif; font-size: 16px;=
 line-height: 16px;">[email protected]</a></p>
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t=3D"_blank" style=3D"text-decoration: none; color: #ffffff; font-family: O=
pen Sans, Helvetica, Arial, sans-serif; font-size: 16px; line-height: 16px;=
">www.example.com</a></p>

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      <tr>
      <td align=3D"center" valign=3D"top" width=3D"157">
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        <tr>
          <td style=3D"padding:0;">
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          </td>
          <td style=3D"padding:0 0 0 15px;">
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_blank" style=3D"text-decoration: none;"><img src=3D"https://example.com/ic=
ons/LinkedIn.png" alt=3D"Link for LinkedIn Channel" width=3D"30" he=
ight=3D"30" style=3D"height:auto;display:block;border:0;" /></a>
          </td>
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ng" alt=3D"Link for Twitter Channel" width=3D"30" height=3D"30" sty=
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我看不到此电子邮件源提取物中的问题 /原因是它掉入垃圾邮件中的原因；有人吗？

然后，我与主机一起检查了有关特定Gmail问题的回复，他们建议我将我的SPF记录更改为：

“ v = spf1包括：_spf.google.com redirect = sharone_host_mail_server_server”，

但我觉得那是这是错误的 /只有在您想通过Gmails Server的域发送电子邮件，还是我错了？

无论如何，关于如何改善结果的任何建议？到目前为止，我不使用DKIM / DMARC，因为我的主机不支持DKIM签名。在这种情况下，尝试通过phpmailer实现DKIM是一个好主意 /如果主机服务器不支持DKIM，是否可以这样做？

在此先感谢您的任何帮助！

PS：我做过此测试，结果是：

对于SPF的两个版本，这都适用于。但是，如果我检查其他工具作为邮件tester或酸上的电子邮件，SPF是有效的。只有fyi