If you send cold emails or have historically, you probably know how important it is to warm-up your IPs and Domains for increased deliverability. But do you know what happens if you skip this critical step and just start sending?

Well, in short – when you start sending emails to thousands of contacts within a single day without a proper IP warm-up in place, you’ll likely get your IPs and domains blocked or even worse, blacklisted.

Mailbox Providers such as Microsoft, want to prevent their mail clients from receiving malicious or spam emails. When they receive too many emails within a short timeframe from the same IP and domain, they’ll start to block those emails from being delivered. You’ll then need to slow the pace of those emails so it mimics a human sender (Learn how to send bulk emails without being Spam).

Why is an Email Classified as Spam?

Each Mailbox Provider, whether it is Yahoo, Gmail, Outlook, etc., has its own defined standards as to how they mark a sender as spam.

When you have no reputation or a low reputation in a new IP or domain, Mailbox Provider is a bit more suspicious when they receive mail from you.

For example: If you create and set up a new email address and then send 1,000 emails on the first day, do you think that the ISPs will notice? The answer is likely yes, and it is especially true if those emails sent are not engaged or if the recipient you sent the email to reports your email to their mail client as spam. This is done by them clicking on the ‘Send to Spam’ button.

They’ll then start to closely monitor how engaged your contacts are with your emails. Do they open your message? Are they clicking the links in the message? Have they replied to your email? These actions taken will improve your overall reputation with that contact’s mailbox provider increase your overall engagement rate. If you get good traffic and engagement rate, then your emails will get delivered to the inbox.

But the opposite is true as well. If your contact doesn’t open your message, marks your email as spam or opt-outs, this decreases your reputation and lowers your engagement score. Enough of these negative interactions and future emails you send to this contact or Mailbox Provider will likely land your message in the junk folder. Or, you’ll get your IP or domain blacklisted.

What will happen if you get yourself on a blacklist?

Well, your emails will likely go straight into the spam folder. This lowers your changes of someone opening this email and reading it. It’ll then lower your engagement score and future emails you send may not even make it past the Mailbox Providers server. Instead, they’ll bounce back. The result is then low delivery rate and inboxing.

This outcome is not ideal and it’s why it’s important to ensure when you send cold emails, you follow best practices. It’s best to warm up your emails by gradually increasing the daily volume of emails sent from your sending variables. Because as the old adage states: slow and steady wins the race.

How do I Know if I am Blacklisted?

Several factors influence a contact opening your email message. Some of them are:

• The time of day.
• The subject line and the preview text.
• The content you’ve written.
• If you are sending emails to your target audience.
• Quality of your list.

However, if you have already done your research… You probably know how to successfully send cold emails and if you have a low delivery rate or are seeing a low response rate, it’s best to check if you’re on a blacklist.

The best tool to use is MX toolbox. With it you can identify if your email domain has landed on a blacklist. This will allow you to make changes on the fly and in real time so you can modify or update to delist yourself from a Blacklist.

In most cases, blacklisted domains will delist after a 2-3 day period with no sending on these sending variables.

Here are some additional best practices you should follow to make sure that when you send cold emails, they won’t get picked up by spam filtering:

Best Practices to Follow When You Send Cold Emails:

• Be sure to follow the anti-spam rules and remain CAN-SPAM complaint.
• Customize your subject lines. They should accurately reflect the information contained in the body of your email and not mislead the recipient. But that does not mean they cannot be creative or imaginative!
• Make sure it your message content is consistent with the brand it represents so recipients recognize the sender and open the email.
• Use segmentation to make emails more relevant and targeted to your recipients.
• Use a true “reply to” address in your email. This is because email providers want to see that you receive responses to the emails you send). Including a legitimate “reply to” address makes it easier for recipients to connect and hopefully avoid potential spam alerts.
• Add an opt-out option to your email. If your recipients open your emails but do not like what they see, this gives them the choice to stop receiving them in the future. An opt-out option for the recipient is a much better alternative than being reported as spam.
• Avoid using spam trigger words, such as GREAT DEAL, ACT! ACT NOW! PLEASE READ, DO IT TODAY, CALL FOR FREE, AND THE LIST GOES ON.

Are you interested in learning more?

Check out HubSpot’s definitive list of SPAM -triggered emails.

Do not add too many links! If you outsource your email campaigns, you need to check how your provider handles the points I mentioned above.

Since you have invested time, energy and, of course, money into building your email list and content, the process of sending your campaign is where can avoid mistakes. The best approach to send cold emails is to use Clickback’s email lead generation software. It’ll automate your sending and you can easily manage your contacts, but it also takes care of the technical challenges of cold emailing as well.

The best rule of thumb is to start with a quality, targeted list from the start. We recommend getting it from a reputable data provider. And don’t forget to continually replenish and maintain the integrity of your list as even the best degrades over time. This is natural as people change jobs and email addresses that were valid can become nonexistent or gets repurposed as spam traps.

Ready to send cold emails? Check out or live 1-on-1 software demo.