Domain & sending warm-up guide
Build sender reputation by ramping volume gradually and mailing your most engaged recipients first. A practical schedule for new domains.
Warming up means starting at a low daily volume and increasing it gradually, so mailbox providers build a positive reputation for your domain before you send at full scale. A new domain has no track record — if it suddenly sends tens of thousands of messages, providers treat it like a spammer and route mail to junk.
MailBlastr sends on a shared IP pool, so the IP reputation is already warm. Your job is to warm up your domain's reputation — which is what Gmail, Outlook, and iCloud actually track for authenticated senders.
The two rules of warm-up
- Ramp volume gradually. Increase how much you send per day in steps, not all at once. Roughly doubling daily volume every few days is a reasonable pace; slow down if you see bounces or complaints rise.
- Send to engaged recipients first. Start with the people most likely to open, click, and reply — recent signups and active customers. Positive early engagement is what tells providers your mail is wanted.
New domain — first-week schedule
A brand-new domain has no reputation, so start very low and roughly double each day. These are baselines, not hard rules — slow down if your metrics worsen.
| Day | Messages per day | Messages per hour |
|---|---|---|
| 1 | up to 150 | — |
| 2 | up to 250 | — |
| 3 | up to 400 | — |
| 4 | up to 700 | 50 max |
| 5 | up to 1,000 | 75 max |
| 6 | up to 1,500 | 100 max |
| 7 | up to 2,000 | 150 max |
Past day 7, keep increasing daily volume in steps (roughly ×1.4 per day is a safe pace for a new domain) until you reach your target, holding hourly volume to about a tenth of the daily figure.
Existing domain — first-week schedule
If you're moving an already-established, already-warm domain onto MailBlastr, you can start higher and ramp faster:
| Day | Messages per day | Messages per hour |
|---|---|---|
| 1 | up to 1,000 | 100 max |
| 2 | up to 2,500 | 300 max |
| 3 | up to 5,000 | 600 max |
| 4 | up to 5,000 | 800 max |
| 5 | up to 7,500 | 1,000 max |
| 6 | up to 7,500 | 1,500 max |
| 7 | up to 10,000 | 2,000 max |
Beyond day 7, continue stepping up (roughly ×1.5 per day for an established domain) toward your target daily volume.
Watch these as you ramp
- Bounce rate — keep it below 4%. A rising bounce rate means list-quality problems; pause and clean before increasing volume.
- Spam rate — keep it below 0.08%. Any climb means slow the ramp and find the root cause before continuing.
- Engagement — opens (with the caveat that they're noisy), and especially clicks and replies.
- For Gmail, watch your domain reputation in [Google Postmaster Tools](https://postmaster.google.com) as you ramp.
After warm-up: stay consistent
Reputation decays when you go quiet. After warming up, keep a steady cadence rather than long silences punctuated by big blasts — a sudden burst after weeks of nothing looks like a fresh, cold sender all over again.