Step 5 - Warmup Schedule

During the warmup phase, delivery stability can be unpredictable. Inbox providers may react variably to volume increases from unfamiliar senders—they might accept all your emails, delay some, or even block your subdomain or sending IP. Therefore, the warmup process often requires adjustments based on the response from each inbox provider.

Some emails, such as transactional messages (e.g., password resets), are critical for your business. We recommend adding an additional 2-week buffer period. This allows you to address any issues with providers proactively and reset if necessary.

Some moments of the weeks and of the year are far from ideal.

Avoid starting a warmup:

• When no one is available to monitor the delivery of your emails and to ask for a mitigation.

• When inbox providers likely cannot answer tickets (e.g., during the weekend).

• When your recipients don't read their emails (e.g., during the weekend, depending on your business) or when they are not interested by your emails.

• When your recipients are already receiving more emails than usual (e.g., Black Friday, Christmas, etc.), as this would decrease the amount of opens and clicks for your emails.

Be sure you maintain good sending permanence during the whole process:

• Don't stop sending emails during the weekend. You should send emails every day

• If you are warming up a subdomain that will send newsletters, focus on emails that are not time-sensitive (e.g., with offers that don't expire, etc.). This is important because you will be sending the same newsletter to different batches of users across several days or weeks

Most inbox providers consider recipient engagement a key factor in determining sender reputation. This includes both positive and negative interactions from recipients.

The warmup phase is crucial for building a positive sender reputation. Here is a recommended approach:

• First 2 weeks: Send emails only to new subscribers and your most engaged recipients (e.g., those who opened or clicked on an email in the last 30 days)

• Until the 4th week: Expand your email sends to include recipients who have opened or clicked on an email in the last 60 days

• By the 6th week: Gradually begin sending emails to users who haven't engaged in 90 days, starting with small batches of emails to mitigate any potential negative impact on your domain reputation

Some automations and campaigns, such as welcome emails and inactivity reminders, might not be ideal for initial sends during a warmup phase, and shouldn't be considered as "transactional" emails:

• Welcome emails: Including these emails in your initial sends might not resonate well with unengaged users

• Inactivity reminders: These users already do not open your emails, and you are likely not legally required to send them

To maximize positive interactions during the warmup, prioritize migrating automations that yield the highest engagement and reassess emails that may be incorrectly categorized as transactional messages.

Automations don't usually have predictable volumes of daily sent emails.

The volume of sent emails is dependent on the activity in your app or your website (e.g., cart abandonment emails, account creation emails, etc.).

As a consequence, finding the right automation to respect the email volume limit set at every stage of the warmup is a complex task.

Here are some tips to navigate this:

• Flexibility: The warmup timeline can be adaptable. Minor variations (e.g., 600 vs 500 emails) are acceptable, but significant deviations should be avoided.

• Prioritize high-performing automations: Focus on migrating automations with the highest engagement first.

• Refine targeting: If daily email volume limits are difficult to meet with specific automations, consider using additional targeting conditions in Batch (e.g., exclude specific countries or languages) to limit recipient pools.

Prioritize migrating high-engagement automations targeting new or engaged users during the warmup phase.

Examples of ideal emails for initial sends:

• Account-related alerts (e.g., account creation confirmation, password reset). Ensure the targeted email addresses are valid to prevent hard bounces that could harm your new subdomain's reputation.

• Order-related (e.g., order confirmation, delivery date). These emails typically have high engagement and minimize the risk of facing issues during the warmup.

Leave win-back automations and abandoned cart reminders for later stages. These emails often have lower engagement and could negatively impact your sender reputation.

• Transactional subdomain: service.domain.com

• Warm-up goal: 1400 emails/day

• Estimated migration time: 3 days

• Newsletters subdomain: news.domain.com

• Warm-up goal: 650K emails/campaign

• Number of newsletters to be sent in batches, before being able to address all your users with a single campaign: 4 campaigns