The purpose of warming up IPs (and, equally important, your sending domains) is to ensure that your new dedicated IP(s) establish a strong sending reputation with the various ISPs where your subscribers have their email addresses. There are multiple factors that can impact your IP/domain reputation, and each ISP may have their own criteria on how they weigh these factors. Because of this, our IP warmup plans try to control three key factors in the process of building up the reputations across all ESPs. These are:

1) Hygiene/quality of email subscriber list (impacts IP reputation)

2) Engagement of users and performance of campaigns (impacts Domain reputation)

3) Volume/consistency of email sending (impacts IP and Domain reputation)

What is a warmup process, why it matters & fundamentals of Reputation?

IP/domain warmup is a process where senders starting to mail off of fresh IPs and domains, gradually ramp up their volumes, while ISPs (internet-service providers) assess the quality of the new mail stream. The goal is to establish a strong sender reputation by slowly ramping up to full volume starting with your most engaged subscribers over a period of time. Typically, this process takes ~4-6 weeks but will vary with each sender depending on a customer’s target volume and engagement.

“IP warming is a pivotal process that can make or break a customer’s ability to successfully reach their customers with email”

Both reputations are important considering that IPs and domains build and maintain separate reputations.

A GOOD WARMUP PERIOD ENSURES THAT YOUR IP AND DOMAIN BOTH BUILD REPUTATIONS WITH ISPs, WHICH INCREASES YOUR CHANCES OF DELIVERING TO THEIR INBOX.

IP/Domain warmup can be one of the biggest pains from migrating from one email service provider to another, so it must be managed strategically and patiently. Basically, there’s no right way to warm up an IP nor is there a specific formula that everyone should follow.

What warming up is about is introducing mail traffic to receiving spam filters in a way that lets the filter know this is a legitimate email stream. This means sending small but regular amounts of mail that recipients interact with. As the filters adjust to the amount of mail from that IP, more mail can be sent over that IP. Increase the mail volume over the next few weeks until the desired volume is reached.

ISPs are cautious about the email activity from new IP addresses. Spammers frequently set up new IPs and immediately start sending large volumes of email. That’s why, ISPs look at previous send history from an IP and/or domain when determining whether to accept, block, or filter a message to their customer’s mailbox. New IPs/domains without any previous history are deemed suspicious to ISPs — “What you have done in the past, is a great indication of what you will do tomorrow.” That’s why warmup process helps ISPs distinguish the legitimate senders from spammers.

7) Monitoring efforts:
- Monitor performance: Bounce and Complaint Rates, Open, Click Through and Click to Open Rates are all ideal metrics to monitor when you are measuring inbox placement & performance.
- If you start getting warning signs (a falling open rate, for example) with Gmail but not with Yahoo, segment your campaigns by ISP and proceed normally with Yahoo while slowing things down for Gmail. Just as you’d segment and personalize your campaigns for different audiences, you should also segment and personalize your campaigns during warmup for different ISPs.
- After every send, monitor your metrics carefully:
      - Have bounce rates increased? Cool your campaign down.
      - Got a spike in spam complaints? Cool your campaign and check that your unsubscribe button is in plain sight.
     - Are open rates dropping? Falling open rates are a sign that you’re no longer engaging your audience. It can also signal and result in your sender reputation dropping. Post Apple MPP, even if we say open rates are not a reliable metric but it is still helpful to analyse in case of any deliverability issues.

- Setup Google Postmaster & Outlook SNDS for monitoring your reputation 7 spam complaints by your domain/IP

- Utilizing seed list or IPTs to monitor inbox placement is also recommended
- Be sure to monitor performance regularly
- Review performance monthly or quarterly to identify trends

8) Scaling your efforts (After the warmup):

- Once you’ve successfully performed a warmup, your inbox placement will have improved. Compared to the below 50% inboxing before warm-up, you can expect 70-90+% inboxing depending on how good your content was after the process is complete.
- As more emails begin reaching your customer inboxes, the higher your chances of converting users. Even if your conversion rate remains the same overall, more people seeing the email will still result in higher absolute conversions.
- After a good warmup program, you can expect a statistically significant improvement in all of your email metrics combined.
- Continue sending to the same hyper-engaged segment, but up the daily limits on your sending.
- If your metrics remain healthy after this, you can slowly add your less-engaged users to the sending list. Just be sure not to add non-engaged users!

So, in a nutshell - Warming up your IP takes time and requires a lot of patience. It’s worth it, though.

- A proper email warm up program gives a significant boost to your first email campaign.
- Think of it as the trust building phase in real-world relationships. Until a person trusts you, you have limited access to their knowledge and resources. Similarly, ISPs won’t let you access their subscribers without first trusting you.
- But once you build up the required trust, they’re happy to deliver more emails from you to their users because they know your emails are useful to their users.
- You can expect your performance to drop a little during the warm-up phases and that’s normal. Once the program is complete, you can bypass the deliverability issues for as long as you maintain the reputation you’ve gained.

Having a productive quality email list is crucial for email marketing success.

That means, your productive quality email list must contain people who actually want to engage with your email programs—and to keep the list healthy, you must keep suppressing people who aren’t engaging.

In short, if you have a healthy & smaller list of more engaged subscribers, you can reach their inboxes more effectively and eventually build a high-performing email marketing channel.

Let’s understand how a healthy email list impacts your email marketing efforts in terms of deliverability, customer relationships, data, and costs.

A productive email list improves sender reputation—and deliverability

If you have a good email reputation, the mailbox providers consider you a trustworthy sender and lands your email into the inbox. The higher the email reputation, the higher the likelihood your emails lands in inbox and vice versa.

Mailbox providers calculate an email reputation based on multiple factors, like:

Permission is not a choice. It's a must for your brand if you really want to build a strong, long term subscriber relationship. A good permission focused list building method can help you not only build a quality list but also empower you to gather their preferences for better targeting and knowing about your subscribers.

However, you'll still find subscribers who signed up for your email list may eventually lose interest or move away from your brand or even stop engaging with your emails. And, in such scenarios, when you don’t clean your list regularly, you’re more likely to keep sending emails to unengaged recipients or hit recycled spam traps, that may have many adverse effects on your reputation & deliverability.

Here are a few best practices that you can follow for list hygiene:

If you are struggling to generate results from your email programs, start with your source of acquisition, how they end up in your list, how frequent they engage with your campaigns and how frequent you clean your email list to keep it healthy.

Content plays a very important role in maintaining high email reputation and deliverability. Your email content has a reputation built with mailbox providers. So as an ecommerce brand or store owner, you need to follow good content practices to maintain a good reputation.

As you know, your deliverability depends on the type of email content you send to your audience. Content is not just about sending anything to your audience and expect they engage and convert. It's not just an art but a science. That's why, we always advise our customers to craft their email content carefully as this will not only build a solid foundation for your email engagement but also, your brand value with your customer.

Follow these email content best practices to make sure that mailbox providers allow your emails to hit their inboxes and be seen by your customers: