Email Deliverability Best Practices

We've compiled a list of best practices based on our conversations with deliverability experts and customers we've helped so far:


1 - Split your marketing and triggered emails

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


2 - Authenticate your email

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. Please refer to this link for more information on setting up DMARC.

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.

3 - Email Link Whitelabel

Email link whitelabels allow all of the click-tracked links to be from your domain instead of 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 it up here.


4 - Customer Data Hygiene

During CRM data import please include all unsubscribes and bounce data from your old platform to Blueshift. Also, make sure the unsubscribe and bounce data is kept in sync during the transitionary period of using old platform and Blueshift via webhooks, apis, segment export, etc. Based on expert opinions, a spam complaint of 1/1000 emails could cause significant reputation damage and particularly as 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. We’ve included a ramp up guideline but this may vary depending on your sending volume

Week 1 Daily Volume
Day 1 200
Day 2 500
Day 3 1,000
Day 4 2,000
Day 5 5,000
Day 6 10,000
Day 7 20,000
Week 2  
Day 8 40,000
Day 9 100,000
Day 10 250,000
Day 11 500,000
Day 12 1,000,000
Day 13 2,000,000
Day 14 5,000,000


  • During weeks 1-2 send to the most active subscribers (opened at least once in last 30 days)
  • During weeks 3-4 send to 60 day active subscribers
  • Do not send to subscribers that have not opened in the past 90 days during the first 45 days of warm up
  • If warming over 5M, do not send more than double the previous volume

6 - Email Content Tips

  • Personalize your content. Take advantage of various Blueshift personalization variables
  • 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
  • Have fewer urls in email. You can see click report in Blueshift and strategically place urls on only the most clicked areas
  • Avoid using unclear or spam flagging subject lines
  • Encourage subscribers to whitelist your From email address, include an “Add us to your address book” link in every campaign you send
  • Include email preview link in your headers
  • Always include and make your unsubscribe link more prominent by highlighting the word Unsubscribe.
  • Include physical mailing address for your business in the footer of your template

7 - Opt-In Email

An opt-in strategy will help to improve your sender reputation and will prevent your emails from ending up in your subscriber’s spam folders. Depending on your business and subscriber base, you could choose to implement Single Opt-in, Double Opt-in or Confirmed Opt-in process.


8 - Implement a Sunsetting Policy

Recipient engagement is extremely important and can affect reputation. Having a sound sunsetting 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. 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.

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