sendmail-wrapper

A powerful sendmail wrapper to log and throttle emails sent by PHP

Advantages

• Lets you monitor any mail traffic from PHP scripts
• Allows throttling (limiting) emails sent by PHP's mail() function
• Throttle by sent email and/or recipient count per day
• Logs both to syslog and database with message metadata
• Logs common mail headers like From, To, Cc, Bcc, Subject
• Fixes Return-Path header on the fly for users who did not correctly set it
• Highly secured setup, customers cannot access the logging/throttling database
• Standalone PHP application without any external library dependencies
• Built for shared webhosting environments where PHP runs in PHP-FPM (FastCGI Process Manager) mode
• No cronjobs required, sendmail-wrapper will reset counters automatically every day

Requirements

• PHP 7.4+
• sendmail compatible MTA: Exim, Postfix,...
• sudo 1.8+

Currently, sendmail-wrapper is tested and actively used by Onlime GmbH on shared webhosting environments with PHP 8.0, 8.1, and 8.2.

Installation

Initial Setup

Clone repository from GitHub:

$ git clone https://github.com/onlime/sendmail-wrapper.git /opt/sendmail-wrapper

Setup system user for sendmail-wrapper:

$ adduser --system --home /no/home --no-create-home --uid 6000 --group --disabled-password --disabled-login sendmailwrapper
$ adduser sendmailwrapper customers

Quick Install

The installer script install.sh will correctly set up permissions and symlink the wrapper scripts:

$ cd /opt/sendmail-wrapper/
$ ./install.sh

If you wish to run this manually, check the following instructions...

Manual Install

Set correct permissions:

$ chown sendmailwrapper:sendmailwrapper *.php *.ini
$ chmod 400 config.private.ini
$ chmod 444 config.ini config.local.ini
$ chmod 555 sendmail-wrapper.php prepend.php
$ chmod 500 sendmail-throttle.php
$ chmod 400 schema/*.sql

Create symlinks:

$ ln -sf /opt/sendmail-wrapper/sendmail-wrapper.php /usr/sbin/sendmail-wrapper
$ ln -sf /opt/sendmail-wrapper/sendmail-throttle.php /usr/sbin/sendmail-throttle
$ /bin/cp -a prepend.php /var/www/shared/

Setup sudo

Add the following lines to your /etc/sudoers:

www-data        ALL = (sendmailwrapper) NOPASSWD:/usr/sbin/sendmail-throttle [0-9]*
%customers      ALL = (sendmailwrapper) NOPASSWD:/usr/sbin/sendmail-throttle [0-9]*

Setup PHP

Add/modify the following in your php.ini:

sendmail_path = /usr/sbin/sendmail-wrapper -t -i
auto_prepend_file = /var/www/shared/prepend.php

NOTE: It is recommended to put the default -t -i options in the sendmail_path directive of your php.ini instead of appending them directly to the sendmailCmd config option in your config.local.ini.

This way, it won't break any projects that use Symfony Mailer component which actually checks for -bs or -t in sendmail_path. (see SendmailTransport.php)

Setup MySQL

Import the sendmailwrapper database schema:

$ mysql -u root -p < schema/schema.mysql.sql

Create a MySQL user with the following permissions:

GRANT USAGE ON *.* TO sendmailwrapper@'localhost' IDENTIFIED BY '********';
GRANT SELECT, INSERT, UPDATE ON sendmailwrapper.throttle TO sendmailwrapper@'localhost';
GRANT INSERT ON sendmailwrapper.messages TO sendmailwrapper@'localhost';

Configuration

Default configuration can be found in config.ini:

[global]
defaultTZ = Europe/Zurich
adminTo = hostmaster@example.com
adminFrom = hostmaster@example.com

[wrapper]
sendmailCmd = "/usr/sbin/sendmail"
throttleCmd ="sudo -u sendmailwrapper /usr/sbin/sendmail-throttle"
throttleOn = true
defaultHost = "example.com"
syslogPrefix = sendmail-wrapper-php
xHeaderPrefix = "X-Example-"

[throttle]
countMax = 1000
rcptMax = 1000
syslogPrefix = sendmail-throttle-php
adminSubject = "Sendmail limit exceeded"

[db]
dsn = "mysql:host=localhost;dbname=sendmailwrapper"
user = sendmailwrapper
pass = "xxxxxxxxxxxxxxxxxxxxx"

You should not change any of the above values. Create your own config.local.ini instead to overwrite some values, e.g.:

[global]
adminTo = hostmaster@mydomain.com
adminFrom = hostmaster@mydomain.com

[wrapper]
defaultHost = "mydomain.com"
xHeaderPrefix = "X-MyCompany-"

Never put your database password in any of the above configuration files. Use another configuration file called config.private.ini instead, e.g.:

[db]
pass = "mySuper-SecurePassword/826.4287+foo"

Upgrading

Upgrade from 1.0.x to 1.1.x

To avoid problems with projects that use Symfony Mailer (Laravel's Mail component also uses Symfony Mailer under the hood!), we have moved the default sendmail command-line options -t -i from Sendmail-wrapper's configuration config.ini to the recommended sendmail_path directive in php.ini. If you stick with our default configuration, you need to update your php.ini:

- sendmail_path = /usr/sbin/sendmail-wrapper
+ sendmail_path = /usr/sbin/sendmail-wrapper -t -i

If you don't care about Symfony Mailer or any other mailer components that check for -t existence in sendmail_path, you can keep the old php.ini configuration and add this to your config.local.ini:

sendmailCmd = "/usr/sbin/sendmail -t -i"