How to send millions of emails

Or better yet how to send millions of emails and avoid getting blacklisted

A simple question with not so simple solution. Sending millions of emails isn't impossible but requires some thinking and work done first.

Even if you did buy your list you should always make sure it is as clean as possible and try to segment it as much as possible. This is hard to do if your bought contact list came only with email addresses. But you could still get info from your contacts like country and what device are they using. Little this can help you with list segmentation and you can better target your audience.

With info like this you can send emails in contacts preferred language and if needed you can split those one mobile and those on desktops. Now imagine having more than 2 custom fields and what it could do to your income. It is possible even if your contacts did not give this info to you one their own.

Once your lists are clean it's time to move them to email marketing application of your choice (read this to see what I'm using) and connect everything with your MTAs/SMTPs.

The flip is an MTA?

You probably know what an SMTP is, but what is an MTA? According to Wikipedia an MTA is:

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. An MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol.

The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with an MX record containing the domain name of the host(s) providing MTA services.

A mail server is a computer that serves as an electronic post office for email. Mail exchanged across networks is passed between mail servers that run the specially designed software. This software is built around agreed-upon, standardised protocols for handling not only mail messages but also any data files (such as images, multimedia or documents) that might be attached to them.

Source: Wikipedia

In short, it's a software that does all the sending. Different MTAs have different features (no shit!) and what we want to be able to send millions of emails are:

  • IP rotation
  • Domain masking
  • Ability to spin content to avoid getting spammed
  • DKIM signing
  • SMTP based limits
  • Domain specific limits
  • Automatic bounce processing
  • Automatic feedback loops processing
  • And so on

Most of this is or at least should be handled by your MTA software. It's important to pick the right one from the start or you will have to redo your complete system and handle all blacklistings before you can finally move forwards with correct MTA software.

What MTA software should you use?

If you ask me the answer is very simple and it’s, PowerMTA. Some might argue but usually, this is because they never used PowerMTA before and don’t know what it’s capable of. There are some alternatives like Postfix, but none come even close when talking about features we need to be able to send millions of emails.

Don’t get me wrong. All MTA software are capable of sending millions and millions of emails, but are they able to deliver them to your contacts inboxes? Can they detect deliverability problems and automatically correct the problem with backoff rules? No, they can’t and PowerMTA if configured correctly can.

The best thing about PowerMTA configuration is that it’s all done in a text file. Of course, this config files can get very long since you can create unlimited domain specific rules, SMTPs, backoff rules and so on. But if you keep it organised everything is very logical and simple.

Is that it?

Of course not. To be able to send millions of emails there is a lot more than needs to be done. Including setting up DKIM, SPF, DMARC, and all other necessary DNS records. To creating all system emails that are required for a bulk email system to work correctly. To setting up reverse DNS and making sure your emails will get a perfect 10/10 score on or other similar services.

The best way to achieve this or at least the way I use and recommend is to follow this DIY guide.