Email deliverability best practices

Email deliverability is whether or not the emails you are sending are reaching the inbox of your recipients. There are a number of factors that can directly influence whether or not your emails arrive in the inbox. A good email deliverability rate is crucial for a successful campaign. 

There are several regulatory measures and laws that help protect consumers around the world. These laws establish requirements for commercial emails and violations can result in heavy fines. You must familiarize yourself with these laws and ensure that your emails are complaints. These regulatory measures include CAN-SPAM Act in the U.S., the CASL in Canada, and the General Data Privacy Regulation (GDPR) in the E.U.

Here are some best practices and tips that will help you to execute a successful email campaign.

1. Authenticate your email domain

Behind every email message there are settings that tell the mailbox provider who you are and if your messages can be trusted.

The two most common authentication methods are Domain Keys Identified Mail (DKIM) and Sender Policy Frameworks (SPF). SPF allows senders to tell ISPs which IPs are able to send on their behalf. DKIM allows ISPs to verify that the content sent is what the original sender intended. There is also a third authentication tool called DMARC (Domain-based Message Authentication, Reporting and Conformance) which works by equipping email recipients with the ability to determine if an email has originated from a legitimate sender.

Authenticating your email with SPF and DKIM proves to the ISPs that you really are who you say you are. Correct authentication is an important starting point for establishing a positive reputation with the ISPs. 

Blueshift’s whitelabeling process ensures that your messages pass DKIM and SPF authentication.

2. Email Link Whitelabel

Email link whitelabels allow all of the click-tracked links to be from your domain instead of the ESP. You may white-label links to use your custom domain by setting up a custom CNAME DNS record to point to . Historically, we have suggested prefixes like “link,” “click,” etc. but you may use any subdomain you would like to use. In summary, custom links are much better for deliverability and contribute positively to your reputation. 

You can set up whitelabels in Blueshift from the Account settings > Other tab.

3. Maintain a strong sender reputation

Most inbox providers look to past recipient behavior to determine whether an email is wanted or not. Focusing on active customers and removing the inactive contacts will show inbox providers that your emails are wanted. This helps you to maintain a strong sender reputation.

Different ISP and filter vendors calculate IP address and domain reputation differently. Reputation is generally based of the following key metrics:

  • Complaint volumes.
  • Spam trap hits.
  • Engagement metrics, such as opens, replies, and moving messages out of the spam folder.
  • Bounces due to invalid addresses.
  • Consistent behavior - no sudden changes in volume.

4. Maintain up-to-date customer lists

Send messages only to customers who have opted-in. Maintain an updated list of subscribers. Use the double opt-in method to add customers to your mailing list only when they explicitly subscribe or opt-in to receive messages.

When you import customer data, ensure that you include all unsubscribe and bounce data. Also, ensure that the unsubscribe and bounce data is kept in sync during the transitionary period of using your old platform and Blueshift via webhooks, apis, segment export, and so on. 

Based on expert opinions, a spam complaint of 1/1000 emails could cause significant reputation damage and particularly when you are rebuilding your reputation.

5. IP Warmup

This is the most critical step in ensuring trust and reputation with ISPs. Email engagement is extremely critical in the initial period and we recommend sending small targeted campaigns to your most engaged customers (someone who has either opened/clicked few times in the last 1 month). You can gradually ramp up this volume and also start including other customers.  

For more information, see IP Warmup.

6. Split your marketing and transactional emails

Marketing emails are much more likely to get blocked due to spam complaints, filters, or traps. Separating your marketing and transaction emails between different, dedicated IP and subdomain/domain combinations will ensure all mission-critical emails get delivered.

7. Write clear and personalized messages

  • Personalize your content.
  • Avoid using unclear or spam flagging subject lines.
  • Do not include all caps, exclamation points, exaggeration and words conveying a sense of urgency in your emails. For example, words like gift, VIP, rewards, ACT NOW, FREE!, No cost, No fees, Limited offer, Bonus, and so on, can trigger spam filters,
  • Do not include videos or Javascript in the emails. Instead use a CTA (like a button with an image) to link to the video on your website.
  • If this is your first email to a customer, keep it short and clear and do not include any attachments.
  • Use good ratio of text to images. Current best practice is at least two sentences of text per image. Messages that are mostly images are less trustworthy to inbox providers and spam filters.
  • Include an alt text for your images. Many email clients block images by default and customers might not see the images when they open the email. Adding alt text to your images helps them understand your message even if they can't see the images.
  • Have fewer urls in email. You can see the click report in Blueshift and strategically place urls on only the most clicked areas.
  • Include an email preview link in your headers.

8. Ask customers to add you to their address book

Encourage customers to whitelist your From email address, include an “Add to your address book” link in every campaign you send. When customers add you to their address book, your emails will not be targeted by spam filters.

9. Provide a way for customers to opt-out

Include a way for customers to unsubscribe or opt-out. If customers are unable to opt-out easily, they might mark your emails as spam and this can affect your Sender reputation. Include a physical mailing address for your business in the footer of your template.

The most common practice is to use an unsubscribe link in the footer of your email or for the customers to reply to the email with Unsubscribe in the subject line. Ensure that this information is clear and easy to locate in the email.

You can also include a preference center which can help customers decide on their level of engagement with you. For example, some customers can opt in to receive communications only about specific topics of interest and other might opt in to receive transactional emails only.

10. Implement a Sunset Policy

Recipient engagement is extremely important and can affect reputation. Sending mail to recipients who are not opening or clicking your messages is one of the quickest ways to damage your reputation. A reasonable benchmark for abuse complaints is 0.1 percent, which means 1 out of every 1,000 people reported your campaign as junk.

Having a sound sunset poIicy can go long ways in maintaining your reputation. Identify which recipients have not opened in more than three months and potentially unsubscribe them (six months is the longest you should send to a non-engaged email address). Alternatively, reduce sending frequency to less-engage recipients or try to engage them with exclusive offers or by asking for feedback.

11. Test your emails before sending them

With Blueshifts email studio, you can preview your emails in popular devices and email clients. You can also send test emails.

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