Domain Warm-Up Rules

When you start sending email from a brand-new domain, inbox providers like Gmail, Outlook, and Yahoo have never seen it before. They have no sending history to judge it by. If you immediately blast thousands of emails from a fresh domain, many of them will land in spam — not because your content is bad, but because rapid high-volume sending from an unknown domain looks suspicious.

Domain warm-up solves this by starting your sending volume low and gradually increasing it over time. As your domain builds a track record of good engagement — emails being opened, replied to, not marked as spam — inbox providers learn to trust it. By the time you reach your full sending volume, your reputation is already established.

Who needs to warm up?

Domain warm-up rules apply on Pro and Agency plans. If you have just added a brand-new domain to TrekMail and plan to send significant email volume, warm-up is strongly recommended.

You typically need to warm up if:

• Your domain has never been used for email before
• Your domain was previously used for email but has been inactive for 6 months or more
• You are migrating from another provider and bringing a large list of contacts

You can usually skip warm-up if:

• You are migrating a domain that has been actively sending email for years and has an established reputation
• You are only sending a small number of transactional emails (password resets, notifications) rather than bulk campaigns

How warm-up works in TrekMail

TrekMail applies a warm-up percentage to your domain's daily sending limit during the warm-up period. Instead of being able to send your full daily allowance from day one, you start with a fraction of it.

The warm-up percentage increases progressively over time as your domain establishes its reputation.

Pro plan warm-up schedule (example progression):

Agency plan warm-up schedule:

Agency plans follow the same progressive model. Because the Agency plan daily limits are higher, starting at 10% still gives you meaningful volume to work with while your reputation builds.

Note: The exact progression and duration of your warm-up period depends on your sending patterns and how inbox providers respond. Domains that see good engagement (high open rates, low spam complaints) may pass through warm-up faster. Domains that generate spam complaints may have their warm-up period extended.

Tips for a successful warm-up

Getting through warm-up smoothly comes down to sending to the right people at the right volume.

Start with your most engaged contacts. During the first weeks of warm-up, send only to people who have recently opened or clicked your emails. High engagement signals to inbox providers that your email is wanted.

Avoid large cold lists. Sending to a list of addresses that have never heard from you — especially old or purchased lists — during warm-up is the fastest way to accumulate spam complaints and damage your reputation before it is even established.

Keep bounce rates low. Sending to invalid or inactive addresses produces bounces. A high bounce rate is a red flag to inbox providers. Make sure your list is clean before you start. Use the TrekMail email verifier to validate addresses before sending.

Monitor your spam metrics. TrekMail shows per-domain spam metrics in the dashboard. Check these during warm-up — a spike in spam complaints is a warning sign that needs attention before you scale up.

Send consistently. Sporadic sending — nothing for two weeks, then a big burst — can slow down warm-up or reset your progress. Try to maintain a regular sending cadence, even if the volume is low.

Checking your current warm-up status

You can see your domain's current warm-up percentage in the TrekMail dashboard:

1. Go to Domains
2. Click on the domain you are warming up
3. Look for the Warm-up section under the domain details

The display shows your current percentage and an estimate of when you can expect to reach full capacity, based on your sending history.

What happens after warm-up

Once your domain completes the warm-up period, the sending cap is lifted and your mailboxes can send up to the full daily limit for your plan. TrekMail applies this automatically — there is nothing you need to do to "complete" warm-up.

From that point on, maintaining your good reputation is straightforward: keep your list clean, make it easy to unsubscribe, and watch your spam metrics. See the production deliverability checklist for a full list of best practices.