The basic purpose of email marketing is to deliver your message to the audience.

Many email marketers struggle to do it rightly. If you are one of them, this ultimate guide to email deliverability has been crafted for you.

Best practices before starting a campaign

Separate the lists: If you send all emails, including newsletters, reminders, and receipts from a single IP and domain, Internet Service Providers will put all of your emails in the promotions folder. That’s why you should prepare different lists for different purposes. After separating the list, use different IPs and email addresses to deliver different emails for each list.

Protect the registration form: A registration or email capture form is the first point of entry of emails into your list. CAPTCHA services like reCAPTCHA or Cloudflare CAPTCHA can protect you from automated bots. These bots are used by scammers and spammers to take unfair advantage of your service. They use disposable or inactive email addresses for registration. The presence of invalid and inactive email addresses means your deliverability rate will be affected.

Verify through double opt-in: A double opt-in process helps us confirm that the user is the real owner of email address.  To deploy this process, you can send a verification link to the email after the user signs-up. This process will ensure only the active email addresses are collected, which means higher deliverability.

Use a real-time API for email verification: A real-time API helps you verify the email address automatically. If the email address isn’t valid, it also warns the user to use a valid email address. You can use an advance service like real-time API by MailTester to verify the emails and enhance the deliverability rate.

Use authenticators: Authenticators like SPF and DKIM help the email servers authenticate the IP and the content of the email. SPF (Sender Policy Framework) authenticates whether an IP address is authenticated to send an email from a domain. DKIM ( Domain Keys Identified Mail) verifies whether the real owner of the domain sent the email or not. Meanwhile, DMARC (Domain-based Message Authentication, Reporting & Conformance ) directs the ISP to take action if an email fails the SPF and DKIM authentications.

After making sure the best practices, we move on to the next part of email deliverability.

Guidelines for better email deliverability

We can take the following measures to improve our email deliverability rate:

Use best DNS and CDN providers

An email is delivered after the records from DNS are retrieved. ISPs also check the reputation of your name servers. You can use a reputed service like Cloudflare  which offers DNS management and customization.

CDN (Content Delivery Network) caches the content before it is delivered. CDN also helps for :

  • Faster load times for images in the emails
  • DDOs protection
  • Advanced firewalls
  • Better deliverability if the CDN provider is reputable

PTR records offer reverse DNS lookup. Internet Service Providers require Forward Confirmed Reverse DNS to send the emails. So always use PTR records for your email delivery.

Send emails in batches

Every email sending platform has set a limit of emails sent per hour. If you cross the limit, your emails will bounce back. For example, Gmail only allows 200 emails/Day per IP.

It’s better to warm the IPs. You can do this by using strategies like sending emails to only those subscribers who opened your email in the last 30 days. You can limit the starting volume of emails to less than 3000. Increase the volume to 4500 after three days, and then double it after ten days. It will keep your deliverability rate safe.

Keep an eye on feedback loops

Feedback loops help you clean your list by checking the complaints received from the receivers. It prevents subscribers from receiving an unwanted email. As a result, you can improve your email deliverability.

Monitor domain health

You can keep an eye on the domain and IP’s health by using the tools provided by ISPs. Google Post Master can give you an idea of spam rate, IP and domain reputation, feedback loops, and delivery problems. Hotmail also offers IP reputation scores, complaints rate, and traps per IP.

Check blacklists regularly

Inclusion in a number of blacklists means less deliverability or no deliverability at all. You should check all the public lists regularly. If you are facing more deliverability issues, you can request your email service provider to check the private blacklists for you. You can read more about blacklists in our detailed guide.

Use whitelisting services

You can use whitelisting services to whitelist your IPs after 90 days of sending an email. Whitelisting helps you improve inbox rate, avoid spam filters, and increase email sending volume.

Have valid MX records

ISPs check for valid MX before allowing your email to be delivered. So, it’s important to have valid MX records.

Respect the un-subscription request

To comply with laws and avoid getting into a blacklist, respect the un-subscription request by the user. It can either be manual or automatic. Make sure to remove the email from the list as soon as possible.

Monitor sender score

The sender score is used to decide whether your email should be allowed or not. That’s why you have to maintain a good sender score, which is 90+. Clean your list, create a @abuse account, and improve your content to increase your sender score.

Maintain quality of your list

It’s important to maintain the quality of the list for better deliverability. Verify whether the email verifier API is set up correctly. Remove all inactive and invalid emails. Do not let the spam traps to get into your list. If you are struggling to do this manually, you can use email list verify service to maintain your list’s quality.


These proven practices will help you improve your deliverability rate. Different ISPs use different spam filters. It’s quite possible that an email might get into a spam folder of Gmail while it lands in Yahoo’s primary inbox. You can use the real-time bouncing feature of MailTester to make sure your deliverability rate always remains high.