How to use HELO with PHP’s mail() function

I originally wrote this for the HELO-community tracker, and it was subsequently published on BeyondCode’s blog, but I wanted to publish it here as well.


HELO works very nicely if you’re sending via SMTP using PHPMailer, SwiftMailer, etc. – but lots of apps and scripts rely on PHP’s clunky old mail() function, which isn’t nearly as easy to deal with, and harder to point at HELO.

You can configure “proper” mail servers like postfix to work as a local relay, but it’s horribly complicated and confusing to set up. Fortunately there are simpler alternatives that are much easier. Searching for local relay tools (what this is) will usually point you at ssmtp, however, that doesn’t work on macOS. A better option for macOS is msmtp which is present in homebrew and works perfectly. I usually run HELO on localhost port 2500, and I configure msmtp with a config file like this, which enables the authentication that HELO requires:

defaults host localhost port 2500 tls off undisclosed_recipients off account default auth plain user test password password

To make the PHP mail function use msmtp, you need to configure the sendmail_path setting in your php.ini file to point at it:

sendmail_path = /usr/local/bin/msmtp -t -i

If you’re using homebrew’s PHP package on macOS, I recommend putting config changes like this in a separate .ini file so that it remains update-safe. For example I put mine in /usr/local/etc/php/7.4/conf.d/marcus.ini.

With those two things in place, PHP’s mail function will submit to the local msmtp binary, which will then relay the message to HELO over SMTP.


Sending via this this route using PHPMailer is very simple because mail() is the default mailer, so you don’t need to configure anything:

<?php use PHPMailer\PHPMailer\PHPMailer; require 'vendor/autoload.php'; $mail = new PHPMailer(); $mail->setFrom('from@example.com', 'First Last'); $mail->addAddress('whoto@example.com', 'John Doe'); $mail->Subject = 'Say Hello to HELO'; $mail->Body = '<h1>Hi!</h1><p>This is my HTML body</p>' $mail->AltBody = 'This is a plain-text message body'; if (!$mail->send()) { echo 'Mailer Error: ' . $mail->ErrorInfo; } else { echo 'Message sent!'; }

Should I build a PHPMailer video training course?

I spend a lot of time working on PHPMailer, and even more answering questions about it on Stack Overflow, yet gain very little from doing so. There is a certain amount of professional pride and reputation involved, but that doesn’t pay the bills. I am lucky enough to have a few GitHub and Patreon sponsors (thank you!), but that doesn’t amount to much. The same questions come up again and again, and repeating the same answers over and over, to people who are convinced that they must be the very first person ever to have had trouble sending email through GoDaddy, gets dull and tiring. I also run Smartmessages.net (a privacy-first email marketing service), so I am continuously exposed to large-scale email issues that small senders never have to worry about, but that are near-impossible to find advice about.

Email is a funny thing; it’s been around forever and is absolutely taken for granted, but it’s horribly complicated (way more so than, say, HTTP), and many developers, especially new ones, have absolutely no idea how it works – hence the repeated mistakes. Email grows more complex by the year, with the addition of things like SPF, DKIM, DMARC, ARC, MTA-STS and more. Some of it is really quite tricky yet the resources available for it either suck or are decades old. I’ve previously pitched book proposals to popular publishers (including O’Reilly and Packt) on “Modern email”, but have always been rejected on the basis that it’s not of interest or “outdated”, even though email usage is forever growing and changing.

So I’ve been thinking about putting together a training video course on using PHPMailer, diagnosing related problems, and using email in general. Such courses are apparently very popular, though I have to admit to not using them much myself, preferring text. I’ve been heartened by the success of projects such as Christoph Rumpel’s Laravel Core Adventures, along with his valuable advice on how he built that. I’ve been impressed by the lovely Jeff Geerling‘s dedication to his ansible book and audience, and have contemplated going the self-publishing route, but a book is a really big commitment, especially on such an enormous subject as email. Video courses are a bit more flexible, though keeping them up to date has its own issues, as Jeffrey Way has said about his amazing output on Laracasts.

The big issue is my audience. I know that it’s going to be primarily junior and novice developers with little experience needing help putting together their first contact form, so it needs to be pitched quite low, at least to start with. I gather that the primary feeder for video courses is social media, but my social media profile (principally Twitter; being a privacy advocate means I really don’t want to go anywhere near Facebook) is mainly more experienced developers, who are probably not the ones who need this kind of help, though you never know – it may just be my impostor syndrome assuming that all these clever people already know about this stuff!

In summary: there is fertile ground for such content, there’s little competition, I’ve got all the experience, equipment, and position needed to do it, but I need some help and encouragement with putting together a platform and reaching my audience. Finally, since I really need to dogfood this sort of thing, please sign up to my PHPMailer mailing list!