Domain Warming

By now, you’ve authenticated your DNS, and it’s nearly time to start sending! However, additional steps are required to prevent spam filtration. We need to be sure and get things right at this stage.

This stat is a bit mind-blowing, so brace yourself: roughly 50% of all emails sent across the internet are spam. As a result, inbox providers treat you as guilty until proven innocent. The onus is on you to prove you’re not a spammer.

If this scares you, that’s a good thing! Deliverability is always a practice of risk analysis and risk assessment, so it’s worth being thoughtful, deliberate, and cautious.

Spam Check Criteria

Inbox providers use aggressive, ever-changing filtering algorithms to automatically flag suspicious mail. How they determine spam falls into a few key categories:

• Domain authentication (we’ve covered this already)
• Sending volume (the focus of this module)
• List health & Message Content (we will touch on these briefly)

Sending Volume?

This is the “surprise” consideration that hurts new senders the most, so it’s a topic you’ll want to pay close attention to early in your sending.

Inbox providers do not like to see sudden large spikes in sending on a new subdomain or envelope domain. Why is this? Well, if you’re an inbox provider, a sudden large influx of mail on a domain could indicate:

• Stolen lists: A bad actor has stolen a list of emails from an external source, and is sending phishing attacks
• Purchased lists: A sender has purchased a list of emails and is, unknowingly or knowingly, violating bulk email sending laws in doing so
• API abuse: A bad actor has accessed your ESPs API keys and flooded your email tool with spam

Even if your intentions and use case are completely legitimate, inbox providers don’t know the difference. You may have a list of highly engaged users you’ve emailed for years, but if you switch ESPs without warming, your launch will lead to delayed deliveries, bounces, and damage to your domain reputation.

What is “Warming”?

Warming your domain is the solution. It is the practice of gradually increasing your email sending volume over days or weeks to make filtering algorithms comfortable with you.

You should absolutely never skip warming. There is no workaround. There is no “safe” way to bypass it. If your ESP representative tells you otherwise, be skeptical. While it may feel like a chore, just remember you only have to do it once.*

Use a warm-up calculator like this one to help plan your email warm-up schedule.