Short answer
To warm up a new sending domain, set up SPF, DKIM and DMARC first. Then start with a few emails a day, raise the number slowly over about 4 weeks and keep your spam rate below 0.1%. Mach warms up a new domain over 28 days, from 20 emails a day to 500, and pauses sending if bounces or complaints rise.
Why a new domain needs time
Mailbox providers decide where your email lands from your history as a sender. A new domain has no history. A sudden burst of email from it looks like spam.
“Start with a low sending volume to engaged users, and slowly increase the volume over time.”
Before you send: set up your records
These records prove that an email really comes from your domain. Google and Yahoo both ask for them.
| Record | What it does | Who asks for it |
|---|---|---|
| SPF | Lists the servers allowed to send for your domain. | Google: every sender needs SPF or DKIM. Senders of 5,000 or more emails a day to Gmail need both. |
| DKIM | Signs each email so the receiver can check nobody changed it. | Google asks for a key of 1024 bits or longer. |
| DMARC | Tells receivers what to do when SPF or DKIM fails. | Google and Yahoo ask bulk senders for it. A policy of none is enough to start. |
| One-click unsubscribe | Lets a person opt out from the inbox in one click. | Google and Yahoo ask bulk senders for it on marketing messages. |
Your email provider usually handles the rest: a reverse DNS record for the sending server, and a secure (TLS) connection.
Use a separate sending domain
Send sales email from its own domain, not your company's main one. If something goes wrong, your everyday mail keeps working. Mach sends from a separate sending domain for this reason.
“Don't send bulk/marketing email from the same IPs you use to send user mail, transactional mail, alerts, etc.”
A warm-up schedule
Raise the number of emails in steps. This is the schedule Mach uses for a new sending domain, over 28 days.
| Step | Emails a day |
|---|---|
| 1 | 20 |
| 2 | 40 |
| 3 | 80 |
| 4 | 150 |
| 5 | 250 |
| After warm-up | Up to 500 |
Write to people who are likely to reply first. Replies help. Complaints hurt.
Watch your spam rate
Your spam rate is the share of your emails that people mark as spam. It's the number that matters most.
“Keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching a spam rate of 0.30% or higher.”
Yahoo asks senders to stay below 0.3%. Mach pauses sending by itself when bounces or spam complaints rise, and you can pause it any time.
What to do while you wait
Warm-up limits email, not the rest of the work. With Mach, research, LinkedIn messages and call scripts can start on day 1. See how it works.
Sources
Checked on 16 October 2026.