[wp-trac] [WordPress Trac] #49687: wp_mail() - Why is no envelope sender defined?

[WordPress Trac]

#49687: wp_mail() - Why is no envelope sender defined?
-----------------------------+------------------------------
 Reporter:  vbbp             |       Owner:  (none)
     Type:  enhancement      |      Status:  new
 Priority:  normal           |   Milestone:  Awaiting Review
Component:  Mail             |     Version:  5.4
 Severity:  major            |  Resolution:
 Keywords:  needs-test-info  |     Focuses:
-----------------------------+------------------------------

Comment (by SirLouen):

 Related #22837

 I've been testing, and as I said in my previous message, the absence of
 `Sender` should not be an inconvenience in 2025 for any reliable local
 MTA.

 Although I tested it in `msmtp` and it reported sender problems without
 the `-f`, confirming that, with some clients there could be a problem by
 omitting this parameter.

 == Testing Protocol

 So from here I will be posting the results using different MTA and trying
 to see if the set to `false` of `auto` in PHPMailer's `setFrom` is
 justified or not.

 === Test 1: Using Postfix for the MTA

 For the first test, I'm using Postfix. WordPress is being reverse proxied
 with a Caddy server but the mail transport agent is not being proxied at
 all. In this case I'm using Postfix 3.7.11 and for wordpress
 [https://core.trac.wordpress.org/ticket/22837#comment:16 these environment
 vars]

 ✅ Email is sent without troubles to a Gmail account

 Here is the resulting email:

 {{{
 Delivered-To: [REDACTED_EMAIL]
 Received: by 2002:a05:6359:6c93:b0:1ff:db44:3f60 with SMTP id
 td19csp103289rwb;
         Wed, 6 Aug 2025 06:45:16 -0700 (PDT)
 X-Google-Smtp-Source:
 AGHT+IHfURwEJp/wfNGBM+hPI0F7isAxnOk4r3ckhMxwX1vbZsw3ltC0TN9XpWt+sLxmFtzIhv22
 X-Received: by 2002:a05:6512:3c8e:b0:55b:8f40:32bd with SMTP id
 2adb3069b0e04-55caf34c5bfmr895771e87.33.1754487916361;
         Wed, 06 Aug 2025 06:45:16 -0700 (PDT)
 ARC-Seal: i=1; a=rsa-sha256; t=1754487916; cv=none;
         d=google.com; s=arc-20240605;
 b=S9gyKcUIAMW7nkD7FEA8EprPJHKLIy8F5eU1Tv+RebjALZEbZNSxPs8WNdqNU95XhH
 5qIkSJ5EZAwkix0A9jVaIdn5d96xC9MhNIiyFgWggjSlGB7oVp3Aa4rhKSgLtzotD/YA
 9vVO4uLU+Hjuw7OA1BB6zWES9h2WO36thEGAIP2ZFQdmTJnrlQqys0kdsCMJEVWvpsjI
 opq7dEIR1ec3vgv6GtN9IIZ8uzpU1gUoXh9LXfGDm1A1rpNe7+5DK75sYMdbOgZWRFXh
 TJzMYrkq3ZizQZCJp+cIMsQ65cAf1QZ7U8BMps2MVrU0YuiYAY228qynnYLHYjVXLW88
          pE5Q==
 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com;
 s=arc-20240605;
         h=content-transfer-encoding:mime-version:message-
 id:from:date:subject
          :to:dkim-signature;
         bh=pm0pN+ANahqck0BActi6j9KgyOF87JJqpDBwwhtS3/8=;
         fh=LnWiZB+0qsThBew1oCwmWb63UJ40SUAv5hSa6DrXbks=;
 b=iVnirhM2bTnFWVwmv39TE/TbEfpAhUeclZtqnmUgwzjESoP66xMu9UxUyIU2xulMop
 e6OYHWPlqNhyvLpcoq3UjqOB66n7EU/ZSylqyjb7uP1FTWQXxQT08VF47APUp710AKmL
 AXBjhDLAjb/TMgBsqqjDHH5rVz1MQZ3ZnywvhnFOAVvXji3UmkFnVvao2oJfLulYcWOO
 4qbTHYni0706+0prjCgal3NoPVTc+9dDAYZnGXJfbd3ozVAjswiX90JvBFMCrvl6783P
 +6aRUWb0ye8dDKIUUI2d90ekfVGvQGpOcGVQoH1LmOytuLlVPH8IWbKP61EJNJD96pUh
          Sq2Q==;
         dara=google.com
 ARC-Authentication-Results: i=1; mx.google.com;
        dkim=pass header.i=@[REDACTED_SERVER_HOST] header.s=mail
 header.b=D6ZD3vYa;
        spf=pass (google.com: domain of wordpress@[REDACTED_SERVER_HOST]
 designates [REDACTED_SERVER_IP] as permitted sender)
 smtp.mailfrom=wordpress@[REDACTED_SERVER_HOST];
        dmarc=pass (p=REJECT sp=REJECT dis=NONE)
 header.from=[REDACTED_SERVER_HOST]
 Return-Path: <wordpress@[REDACTED_SERVER_HOST]>
 Received: from [REDACTED_SERVER_HOST] ([REDACTED_REVERSE_HOST].
 [[REDACTED_SERVER_IP]])
         by mx.google.com with ESMTPS id
 2adb3069b0e04-55b887df9ebsi4154730e87.107.2025.08.06.06.45.15
         for <[REDACTED_EMAIL]>
         (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
         Wed, 06 Aug 2025 06:45:15 -0700 (PDT)
 Received-SPF: pass (google.com: domain of wordpress@[REDACTED_SERVER_HOST]
 designates [REDACTED_SERVER_IP] as permitted sender) client-
 ip=[REDACTED_SERVER_IP];
 Authentication-Results: mx.google.com;
        dkim=pass header.i=@[REDACTED_SERVER_HOST] header.s=mail
 header.b=D6ZD3vYa;
        spf=pass (google.com: domain of wordpress@[REDACTED_SERVER_HOST]
 designates [REDACTED_SERVER_IP] as permitted sender)
 smtp.mailfrom=wordpress@[REDACTED_SERVER_HOST];
        dmarc=pass (p=REJECT sp=REJECT dis=NONE)
 header.from=[REDACTED_SERVER_HOST]
 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;
 d=[REDACTED_SERVER_HOST]; s=mail; t=1754487915;
 bh=pm0pN+ANahqck0BActi6j9KgyOF87JJqpDBwwhtS3/8=;
 h=To:Subject:Date:From:From;
 b=D6ZD3vYaKdxPsALFXP83772Yse7M6tXkW2wr4vOieEtliFq7Nd6mkixbXjmro86eB
 HdgwiUG022juBDRpsgLsQz+m2xeyWfMYZ4Bbbk3x9xcT+f7Utmvo1UjCfl9re8KAgc
          uvISwsJ+gUKmWA596tyGG+WFLYG6BzI2+UhxlgXo=
 Received: by [REDACTED_SERVER_HOST] (Postfix, from userid 33) id
 978A121C0B; Wed,
   6 Aug 2025 13:45:15 +0000 (UTC)
 To: [REDACTED_EMAIL]
 Subject: Health Check – Test Message from https://[REDACTED_SERVER_HOST]
 Date: Wed, 6 Aug 2025 13:45:15 +0000
 From: WordPress <wordpress@[REDACTED_SERVER_HOST]>
 Message-ID:
 <DAeEY8uz0xzBIMrxcRcH6kvrJTLBuK1nTutUOIJ1o@[REDACTED_SERVER_HOST]>
 X-Mailer: PHPMailer 6.9.3 (https://github.com/PHPMailer/PHPMailer)
 MIME-Version: 1.0
 Content-Type: text/plain; charset=UTF-8
 Content-Transfer-Encoding: 8bit

 Hi! This test message was sent by the Health Check plugin from WP Testing
 (https://[REDACTED_SERVER_HOST]) on August 6, 2025 at 1:45 pm. Since
 you’re reading this, it obviously works.

 Additional message from admin: This is the first test
 }}}

 Note that since this is sent via Postfix and Postfix works correctly both
 setting `-f` and without, it will work the exact same in both scenarios.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/49687#comment:14>
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