The Problem:
When utilizing Laravel’s email functionality with SMTP, it’s common to configure settings in the config/mail.php configuration file or the .env file.
One crucial parameter is the local_domain or MAIL_EHLO_DOMAIN, which specifies the domain used when communicating with the email server during the Extended Simple Mail Transfer Protocol (ESMTP) negotiation.
In the absence of a proper MAIL_EHLO_DOMAIN setting, Laravel defaults to using the localhost IP address (127.0.0.1) as the local domain. This default behavior can lead to issues, as illustrated in the provided logs. Emails sent may be bypassed or marked as spam, causing potential delivery failures.
These are the types of restrictions that can cause an email to trigger the filter:
HELO: WIN-${11 numbers and/or letters}
HELO: [127.0.0.1]
Message-ID: <CHILKAT-MID-
Message-ID: <[0-9]{8,10}\.[0-9]{14}\@$sender_helo_name
The Solution:
To address this issue, developers should explicitly set the MAIL_EHLO_DOMAIN in the Laravel configuration files (config/mail.php or .env).
In the example configuration snippet below, the local_domain parameter is set to ‘sh003.bigrock.com’ which is the hosting server hostname:
'mailers' => [
'smtp' => [
'transport' => 'smtp',
'host' => env('MAIL_HOST', 'sh003.bigrock.com'),
'port' => env('MAIL_PORT', 465),
'encryption' => env('MAIL_ENCRYPTION', 'ssl'),
'username' => env('MAIL_USERNAME'),
'password' => env('MAIL_PASSWORD'),
'timeout' => null,
'local_domain' => env('MAIL_EHLO_DOMAIN', 'sh003.bigrock.com')
],
],
Logs without MAIL_EHLO_DOMAIN:
In the provided logs, the absence of the MAIL_EHLO_DOMAIN setting results in the default IP address of localhost (127.0.0.1) being used as the mail helo server. This can lead to email verification messages being bypassed, as seen in the ‘bypassed’ status in the log entry.
2024-02-16 20:15:18 1razSo-003pzE-2H <= developers@visitinglink.com H=sh003.bigrock.com ([127.0.0.1]) [162.241.85.168]:35070 I=[162.241.85.168]:587 P=esmtpsa X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no A=dovecot_login:developers@visitinglink.com S=13581 id=4debb5a4266b1bef0e2a494a82e639cf@visitinglink.com T="Verify Email Address" from <developers@visitinglink.com> for mailhostingserver22@gmail.com
2024-02-16 20:15:18 1razSo-003pzE-2H => /dev/null <mailhostingserver22@gmail.com> F=<developers@visitinglink.com> R=fightspamHG T=**bypassed** S=0
Logs with MAIL_EHLO_DOMAIN:
When MAIL_EHLO_DOMAIN is properly configured, as shown in the logs, the email server negotiates with the specified server(‘sh003.bigrock.com’). This ensures proper identification and authentication, leading to successful email delivery without being bypassed or marked as spam.
2024-02-16 20:15:44 1razTE-0040ir-1m <= developers@visitinglink.com H=sh003.bigrock.com [162.241.85.168]:32756 I=[162.241.85.168]:587 P=esmtpsa X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no A=dovecot_login:developers@visitinglink.com S=13564 id=6c3e52012d134bf7ecf99d0b23c300e5@visitinglink.com T="Verify Email Address" from <developers@visitinglink.com> for mailhostingserver23@gmail.com
2024-02-16 20:15:44 1razTE-0040ir-1m Sender identification U=walltein D=visitinglink.com S=developers@visitinglink.com
2024-02-16 20:15:44 1razTE-0040ir-1m Sender identification U=walltein D=visitinglink.com S=developers@visitinglink.com
2024-02-16 20:15:45 1razTE-0040ir-1m => mailhostingserver23@gmail.com F=<developers@visitinglink.com> R=dkim_lookuphostHG T=dkim_remote_smtp S=15511 H=eig-west.smtp.a.cloudfilter.net [34.223.136.48] I=[162.241.85.168] X=TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=yes DN="/C=US/ST=California/O=Proofpoint, Inc./CN=*.smtp.a.cloudfilter.net" C="250 azTErf1mH2ESoazTFrpDVY mail accepted for delivery"