To set the scene. Firstly, you should never be hosting emails on your web server, it is extremely bad practice these days for a variety of reasons, read the following for why; Really Simple Guide to Business Email Addresses, Really Simple Guide to Web Servers, Really Simply Guide to Web Server Security, The Importance of Decoupling Your Digital Services and most importantly, just use Microsoft Exchange for your email system.
Ok, so now we’ve got that out of the way, let’s look at some of the other practicalities of web application development. Most, if not all, web applications require you to send emails in some form to a user. Whether this is a subscriber, a member, an administrator or someone else. Which is why it is important to make sure these emails are being received in the best possible way by those people and not getting missed in the junk folder, or worse, automatically deleted which some email systems actually do.
Sending emails from your web application is not always the most straight forward task and hugely depends on your web server configuration, the underlying technology and more. So we aren’t going to cover how to do this within this blog post, instead we are going to assume that you have managed to implement this and are now stuck wondering why your emails are ending up in your and your customers junk folders. The answer to this is often simple, it’s because your email looks like spam, even though it isn’t.
Introducing Sender Policy Framework (SPF Records)
The Sender Policy Framework is an open standard which specifies a technical method to prevent sender address forgery. To put this into perspective, it is unbelievable simple to send a spoof email from firstname.lastname@example.org. Sending spoof emails was something I was playing around with my friends when still in high school at aged 14, sending spoof emails to each other for a bit of fun and a joke.
Because it is so simple to send spoof emails, most email providers (Microsoft Exchange, Hotmail, Outlook, Gmail, Yahoo etc.) will often automatically classify emails as spam if they aren’t identified as a legitimate email. A legitimate email in this sense is an email that has been sent from a web server which is handling the Mail Exchanger technologies.
To step back a little. The Mail Exchanger, is a record which is set at the DNS level which is referred to as the MX record. What this record does is that whenever someone sends an email to email@example.com, the underlying technologies of the internet route this email to the server which is handling your emails, the server which is identified within your MX Record at your DNS. The server then does what it needs to do when receiving this email so you can view it.
For example, when hosting your email on your web server with IMAP (as explained before, you shouldn’t be doing this), your MX record will likely be set to something along the lines of ‘mail.your-domain.com’. When using Microsoft Exchange, your MX record will be something along the lines of ‘your-domain-com.mail.protection.outlook.com’.
What this means is that if an email is sent from @your-domain.com which hasn’t come from one of the IP addresses attached to your-domain-com.mail.protection.outlook.com, then this looks to have been sent by someone who is not authorised to send emails from your domain name, and hence why this email will then end up in the spam box.
With Microsoft Exchange specifically to use this as an example, you will also have an additional SPF record attached to your DNS as a TXT type which will look something along the lines of, ‘v=spf1 include:spf.protection.outlook.com -all’, which translates as, the IP addresses associated with the domain spf.protection.outlook.com are allowed to send emails from the @your-domain.com email address, and deny everything else.
This is perfect for standard use, but doesn’t work so well when trying to send emails from a web application. Which is why we need to configure the DNS records to make the web server which is sending emails from your web application a valid sender too.
How to Configure your DNS with SPF Records
To do this, we simply add the IP address of your web server into the DNS TXT SPF record as follows;
v=spf1 include:spf.protection.outlook.com ip4:123.456.123.456 –all’
Your records will likely be different, so please don’t just copy and paste the above into your DNS. Make sure you adapt this to your individual needs. That is it. Now when your web application sends emails to your users, they will arrive in their main inbox instead of their junk folder. Simple.
A few handy tools for diagnosing DNS propagation along with SPF testing include;
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