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IP warming best practices for enterprise brands

6 Minute Read

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Steve LunnissHead of Deliverability, Cordial

Email marketers implement IP warming to establish their reputation with internet service providers (ISPs). This process helps to ensure that emails reach the recipient’s inbox and don’t end up in their spam folder. By warming IPs, marketers can improve deliverability rates, maximize open rates, and ultimately drive more conversions.

Why do you need to do IP warming?

IP warming is the process of gradually increasing the number of emails sent from a specific IP address over a period of time to build a positive reputation with ISPs. It’s important for marketers to warm their IPs before sending out large volumes of emails, as failure to do so will likely lead to their emails being blocked or junked.

While this may seem like a tedious task, the benefits of IP warming for marketers are numerous:

  • Email acceptance rates will improve
  • Emails will reach the inbox rather than the spam folder
  • ISPs will learn to trust you as a legitimate, responsible sender
  • Subscribers will have more opportunity to engage with your emails
  • You will see a better ROI from your email marketing campaigns

How long can IP warming take for enterprise brands?

A good estimate is it takes roughly 30-45 days to warm a set of IPs. However, there are many variables at play that can affect the time it takes, such as:

  • Data hygiene: The quality of your data can have a huge impact on the outcome of the ramp plan. Hitting lots of traps, disengaged or churned subscribers, and typo addresses will negatively impact your reputation with the ISPs. It is advisable to run your data through a cleaning tool prior to ramping and to only target those who have recently engaged.
  • Frequency: The frequency of which you send is important. Having a regular cadence of sending will assist in keeping the process on track. Having multiple days of inactivity causes the IPs to cool down and also trigger a red flag at the ISP for abnormal sending patterns.
  • Volume: The size of your audience comes into play. Of course, the larger the database the larger the pool of IPs that are required — and the longer it will take to get the IP fully warmed to your business as usual send volume.
  • Content: During the ramp process you may need to send more campaigns than you usually would. You should plan ahead and make sure you have enough good content ready to send so that your subscribers continue to engage.

Example of promotional campaign warm-up plan:

Cordial IP Warming Ramp Up Volume Chart Example for Gmail, Hotmail, Outlook, Verizon/Yahoo/AOL (VMG) and all other domains. Daily volume and send # by day.

Common terms for your teams to know during the IP warming process

There are a number of terms that you will likely come across while navigating through the IP warming process:

  • Sender reputation: Your sender reputation is essentially a score created by the ISPs against your IP/domain to determine whether you are a good, responsible sender. Microsoft and Gmail have tools that allow you to see what your reputation is in their eye.
  • Email validation: Email validation involves use of a tool that checks the syntax, spelling, and, in some cases, mail exchange (MX) records of the recipient domain to see if it actually exists.
  • Soft bounce: A soft bounce is generally a temporary error, such as a full mailbox, where the receiving ISP cannot accept the email at this time but may accept it later.
  • Hard bounce: A hard bounce is when the email is permanently rejected due to reasons such as the recipient domain does not exist or the account is no longer valid.
  • Blacklists: There are a number of not-for-profit organizations that will put you on a blacklist and make that information available to the ISPs if you are deemed as spamming and/or have poor data acquisition processes.
  • SNDS: Smart Data Network Services is a free reporting tool provided by Microsoft where you can monitor the reputation of your dedicated IPs and request support for deliverability issues.
  • GPT: Google Postmaster Tools is a reporting platform provided by Google to see how they view your IP and domain reputation. You can request support and read about best practices.

The following three items are all authentication methods that can be used in conjunction with each other to help stop spammers from sending phishing messages:

  • SPF: Sender policy framework
  • DKIM: Domain Keys Identified Mail
  • DMARC: Domain-based Message Authentication, Reporting & Conformance

Best practices for IP warming

In order to give yourself the best chance to be successful in building a good long standing reputation you can start by following these steps:

  • Authentication: When setting up DKIM, SPF, and DMARC, you are immediately showing the ISPs that you are who you say you are and are actively taking steps to ensure your subscribers are not phished from your domain.
  • Segmentation: Sending emails to only those subscribers who are engaged with your emails will ensure your reputation builds quickly and keeps the negative interactions (spam complaints and unsubscribes) to a minimum.
  • Content: Make sure you are sending emails with relevant and interesting content to your subscribers.
  • Subject line: While open rates are now hard to measure, it is still worth investing time into creating exciting subject lines that will draw the attention of the subscriber.
  • Reporting: Keeping a close eye on performance by domain group (Microsoft, Gmail, Yahoo ,and Global) will help you quickly identify if you are under performing at any of the ISPs.

IP warming is an essential part of any email marketing strategy, as it helps marketers to establish a positive reputation with ISPs and improve deliverability rates. By following the steps outlined above, marketers can ensure that their emails reach the recipient’s inbox instead of their spam folder and maximize open rates and conversions.

Ultimately, IP warming can be a powerful tool for email marketers if done correctly. By taking the time to prepare and execute the process properly, marketers can reap the rewards of improved deliverability rates and overall better email performance.


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