Don’t Send Email Without It: The Art of IP Warming

Trust isn’t earned overnight. Strong customer/brand relationships are built on a foundation of smart, reliable communication over time. The same holds true for the relationships brands have with the ISPs that oversee what emails customers actually receive. As a rule, ISPs rely on you to deliver quality messaging to their users—and if they can’t trust you do that, your emails may never make it to your customers’ inboxes.

ISPs will accept you (and your messages) if they trust that you’re not going to spam their users with unwanted emails. But they can’t confidently determine that you’re a legitimate sender if they have no prior sending behavior, patterns, or history to look at for reference. In order for you to gain the ISPs’ trust and confidence, you’ll have to prove to them that you’re the real deal with your actions. This process of ISP courtship is commonly known as an IP warm-up.

An IP warm-up is a period of time where you’re working to establish your sender reputation by slowly scaling up the volume of your email sends. This generally take 4-6 weeks, though it can take longer depending on your brand’s planned monthly email volume, frequency of mailings, and overall list hygiene (your number of valid email addresses, email addresses confirmed via double opt-in, active subscriptions, etc).

In order to protect their users from unsolicited and unwanted email, ISPs will always err on the side of caution when dealing with new IPs. If your sender reputation is low, that means your messages will be filtered into the spam folder or worse, blocked. If an IP address isn’t properly warmed up and you suddenly start sending a high volume of messages in a short span of time, it could take weeks (or even months) to recover from that mistake. Here are some true and tested IP warming best practices that can help you can avoid prolonging the warming period:

1. Check that your infrastructure and authentication pieces are all tidied up before sending. This means updating your DNS records, passing SPF, signing with DKIM, and securing your systems. Here at Braze (formerly Appboy), we set up white label domains for all of our clients that send email through us so they can authenticate themselves as legitimate senders.
2. Sign up for all available feedback loops and remove email addresses the first time they complain about your mail. You’ll want to avoid consistently sending to people who don’t want your emails during this sensitive period. Since receiving additional complaints from them is likely, this will further harm your sender reputation. We setup our clients on these feedback loops and will immediately suppress any email addresses that have marked your email as spam from future marketing campaigns.
3. Send your emails to people who are most likely going to open them, click through links, reply to them, or forward them to others, in small, incremental quantities first. (You know, your most engaged users.) These same group of users should also be least likely to delete without reading and mark them as spam. Braze clients are provided a warm-up schedule which we strongly encourage them to follow, because slow and steady wins the race here. This schedule—coupled with sending to your most engaged and active subscribers first—will quickly build up your sender reputation. This is also an opportunity for you to clean up your database by removing all invalid email addresses using an email validation service and sunsetting extremely inactive and lapsed users.
4. Send low-risk, relevant, and high performing campaigns you know your subscribers want and are more likely to open. Maybe you have a promotion or coupon code that always generates high engagement from your users or you have a weekly newsletter or digest your subscribers expect to receive and regularly read. Avoid changing your creatives, templates, or rolling out any new emails during this period, since you don’t know how your subscribers will react. Just like how mailbox providers are careful with a new IP, you should be extremely cautious as well with new content or emails your subscribers have never received before either.
5. Monitor your email metrics very closely on each warm-up day and adjust your volume as needed if you see any issues arise. With Braze Email Solutions, we offer email reporting to help you analyze and measure the success of your campaigns like delivered rate, bounced rate, open rate, click rate, spam rate, and more. To learn more about email metrics that count, check out our post on Email Benchmarks That Really Matter.

Anything else?

Advice on IP warming from Braze Senior Customer Success Manager Nicole Codd

Following the recommended strategies above will set your IP warm-up up for success while also establishing a positive sender reputation at all ISPs. This means your email messages are being delivered and seen by your customers, which sets the stage for you to start crafting targeted, contextual, and highly personalized experiences.