Who This Is For / When to Use
This article is for Kyrios users sending email from a dedicated domain who want to improve deliverability and avoid spam filtering by following a controlled, reputation-safe warmup process.
What Is Email Domain Warmup?
Email domain warmup is a controlled process that slowly increases how many emails a domain can send each day. This gradual increase helps inbox providers trust the domain and reduces risks such as spam filtering, bounces, or delivery delays.
Kyrios uses a fixed-stage warmup model with predefined daily limits to ensure consistent and predictable progression.
Key Features and Benefits
The warmup system is designed to protect sender reputation while allowing scalable growth.
Key benefits include:
Improved inbox placement and reduced spam filtering
Automatic tracking of sending limits and stage progression
Fixed, predictable daily limits per stage
Visibility into warmup progress directly in the domain dashboard
How the Fixed-Stage Warmup Model Works
Each domain progresses through predefined stages with increasing daily send limits.
Daily Sending Limits by Stage
The table below shows the fixed daily limits applied at each stage of warmup.
Key rules:
Each stage has a daily sending limit
There are no hourly limits, only daily limits
Progression occurs only when the full daily limit for the current stage is reached
Sending activity must come from the warming domain
Sending Beyond the Daily Limit
Kyrios does not block sending after the daily warmup limit is reached.
When the daily limit is exceeded:
Emails continue to send without interruption
Additional sending does not count toward stage progression
The domain pauses warmup progression until the next day
At 12:00 AM UTC, the system resets the daily counter. If the previous day’s limit was met, the domain automatically advances to the next stage.
When Warmup Starts
Warmup behavior depends on whether the domain is new or already active.
Newly Created Domains
For newly created and verified domains, warmup starts automatically. No manual configuration is required.
Existing Domains
For existing domains, warmup must be started manually. Kyrios analyzes historical sending activity and available reputation data to recommend the safest starting stage.
How to Start Warmup for an Existing Domain
Admins can manually enable warmup from Email Services.
Go to Account Settings.
Click Email Services.
Select SMTP Service.
Open the Dedicated Domain and IP tab.
Choose the domain.
Click Start Warmup.
Google Postmaster Tools Integration (Recommended)
Connecting your domain to Google Postmaster Tools provides visibility into how Gmail views your sending reputation.
Postmaster data includes:
Domain reputation (High, Medium, Low, Bad)
Spam complaint rates
Authentication status
Delivery errors and volume metrics
If Postmaster data is unavailable, Kyrios displays guidance to help complete the setup.
Best Practices for a Successful Warmup
Following best practices ensures stable progression through all stages.
Recommended actions:
Send emails consistently every day
Use verified, opt-in contact lists only
Avoid sudden volume spikes
Respect daily sending limits
Do not change the sender domain mid-campaign
When Warmup Is Complete
Warmup is complete when the domain reaches Stage 15, which supports up to 250,000 emails per day.
Once complete:
A Warmup Complete status appears in the domain dashboard
Full-scale sending is supported without warmup limits
Common Issues and Fixes
Progress is not advancing to the next stage
This happens when the full daily limit is not reached.
Fix: Ensure the domain sends the entire daily quota for the current stage.
Deliverability issues during warmup
Poor list quality or sudden spikes can harm reputation.
Fix: Use engaged, opt-in contacts and follow daily limits strictly.
Frequently Asked Questions
What happens if I exceed the daily sending limit?
Sending continues normally, but extra emails do not count toward stage progression.
How long does the warmup process take?
Warmup typically completes in two to three weeks, depending on the starting stage and sending consistency.
Can I use any email lists during warmup?
Only verified, opt-in lists with engaged recipients should be used.
Can I change my sender domain during warmup?
No. Changing the sender domain disrupts reputation building and may cause deliverability issues.
How does Kyrios choose a starting stage for existing domains?
Kyrios evaluates historical sending activity and Google Postmaster data to recommend a safe starting stage.