Amidst the Coronavirus pandemic, many email programs drastically changed their mailing strategy and cadence for a multitude of reasons.

While this might make sense for your brand and your audience in the face of this pandemic, a significant ramp-down or complete pause in sending could impact your program’s deliverability when you’re ready to start mailing again.

Email inbox providers (ISPs) monitor the volume of messages you’re sending and use this information to help determine your sender reputation; severe peaks and valleys or sudden increases in volume are consistent with spam, and could get your messages sent to the spam folder, or blocked altogether.

To maintain strong deliverability your ramp-up plan should include slow and consistent increases to send volume in order to rewarm your IPs and domain. 


1. Why a “Warm-up” Plan is Necessary


If you’ve paused or reduced your campaign and trigger volume for one week or more there are simple warm-up strategies you can implement to ensure you maintain your positive sender reputation as you resume normal cadence.

The goal of a warm-up plan is to increase your sending volumes back to your anticipated “normal” level.

You want ISPs to re-learn your usual sending habits so they can clearly identify you as a good sender. Pausing for 1-2 weeks will require a very short warm-up window, but if you’ve paused your program for more than three weeks it will be a heavier lift to resume sending at normal volumes.

During this time, ISPs will monitor your sending practices, list health, and content relevancy through subscriber engagement. The plan below details how to segment your audience, prioritizing the most likely to engage contacts early in the process to send signals to ISPs that your recipients do, in fact, want to receive your messages. 

Taking the time to properly re-warm your IPs and domain will make your life easier long term and ensure you can focus on your program strategy instead of chasing down deliverability issues.


2. What Should Your Warm-up Plan Look Like?


ISPs keep sender data for up to 30 days on average, so the length of your send pause will determine how you should plan to increase your send volume.

“If you are a brand new sender, you’ll want to follow a more stringent plan for warm-up compared to what we’ve outlined below. Although the daily volume may have changed, domains are still able to see some level of reputation from your previous campaigns.”

— Kellie Collins, Senior Strategist & Deliverability Expert


“If you’re a net-new sender, some providers, like Gmail, prefer seeing even lower deliveries on the first day compared to the 20 we’ve recommended starting with here, while others, like Microsoft, prefer to see deliveries stay consistent for a 3-day period vs. ramping up each day,” explains Collins.

Below are three scenarios to help guide your re-warming process based on the length of your mailing pause.

For all campaigns and/or triggers paused for 1-2 weeks


If you paused your sends or reduced the volume by more than half for 1-3 weeks you should follow the below steps:

Day 1: Turn on automations.

Day 2: Review open rates by domain across automations.

Day 3: If automation performance looks good, throttle a batched campaign over a few hours, and monitor open rates by domain closely.

Day 4: If performance looks good you can proceed with normal sending, continuing to monitor engagement in early weeks for signs of issues.


For all campaigns and triggers paused for 3-4 weeks


If you paused all sends for 3-4 weeks you should follow the below steps:

Day 1: Turn on high engagement automations that would account for roughly half of the total automation send volume.

Day 2: Review open rates by domain for automations.

Day 3: If automation performance looks good, start sending your first batched campaign with the audience split up by engagement, prioritizing most engaged users first (generally identified by recency of last open and click) so your initial sends show the highest engagement possible.

Once the audience is split into 3 groups from highest to lowest expected engagement you can send group 1 the campaign.

Day 4: Review open rates by domain for the campaign (and third party tool results if applicable).If performance looks good, send the campaign to group 2.

Day 5: Review open rates by domain for the campaign and if performance looks good, send the campaign to group 3.

Day 6: Review open rates by domain for automations and the campaign and if performance looks good you can proceed with normal sending. 


For all campaigns and triggers paused for 4+ weeks


If you paused all sends for 4+ weeks you will need to go through a full warm-up plan similar to the below:


Week 1: Turn on Welcome Automation Series (if paused). If the Welcome Series was still running, turn on your Cart Abandonment Series.

Week 2: Identify a small group of recently engaged contacts (clicked or opened email) and segment these contacts by domain (Gmail, Microsoft, OATH, and All Other Domains).

Pull 20 random subscribers from each highly engaged segment to send your first campaign (80 total contacts).

Over the next 4 days pull another set of random contacts (not including anyone that already received the email) and double the size of your audience each day. 

Over the course of 5 days, you should run one campaign to 80, 160, 320, 640, and 1,280 contacts split evenly between the 4 ISP groups.  

Expert Tip: During the warm-up process it is ideal to pause sending on the weekends to ensure you can easily monitor performance throughout the day and adjust as needed.

Week 3: Expand your engaged segment slightly and segment these contacts by domain (Gmail, Microsoft, OATH and All Other Domains). 

Send your campaign to new randomized contacts from each ISP group while continuing to double your daily send volume from last week.

At the beginning of the week turn on 1-2 additional triggers that are moderate in volume.  You can also deploy one email to the warmed contacts from Week 2. 

Week 4: Repeat the same process with segmentation from the previous weeks and continue to double daily send volume. Turn on any remaining paused automation. You can also deploy one email to the warmed contacts from Week 2 and 3. 

Week 5: You should be at your previous send volume and can resume normal sending habits.


3. Don’t Forget to Measure Your Email Deliverability


The two key areas to determine your inbox placement are open rates by domain and a third party inbox tracking tool like 250ok or Return Path.

It is possible to complete a warm-up plan based solely on open rate by domain if needed. You can read Email Deliverability 101 for more detailed information. 


Final Takeaways


This slow ramp-up will allow you to quickly adjust your strategy before your sending reputation is impacted.

The main takeaway for any type of warm-up plan is to start slow, sending to most engaged contacts first and reviewing your metrics daily so you can adjust quickly to prevent damage to your sender reputation. 


  • After each send, you should be monitoring open rates by domain for changes in performance.


  • If you have an inbox monitoring tool, send it to the seed list once before you begin the warming process and then once per week throughout.


  • The size of the seed list should be less than 10% of your total deliveries on the days you are sending campaigns and to the seed list. ISPs are basing deliverability on engagement and seed lists may negatively impact your overall performance if you have a smaller list size.


“As you’re monitoring performance, keep in mind that each domain operates differently using their own proprietary algorithms to determine inbox placement,” says Collins.

“Be sure you’re reviewing campaign performance at the domain level to determine if you’re safe to expand that group OR if you need to pull back a specific domain. It’s possible it may take longer for some domains to ramp back up than it will others.”


If your sending has ramped back up, but you are still uncertain of your general deliverability then take advantage of Tinuiti’s Free Email Marketing Deliverability Review.  

If you need more expert tips to navigate your marketing strategy through the Coronavirus visit the Tinuiti COVID-19 Resource Hub and Marketing During Coronavirus: Your Top Questions Answered.


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