How to warm up a new email domain: the order of steps, how long it takes and when a tool helps

How to warm up a new email domain: the order of steps

• Step 1, authenticate: publish SPF and DKIM for the sending domain and add a DMARC record. Google requires SPF or DKIM from every sender, and SPF, DKIM and DMARC from senders of 5,000 or more messages a day to personal Gmail accounts. Use a DKIM key of at least 1024 bits; Google recommends 2048.
• Step 2, monitor: add the domain to Google Postmaster Tools and verify it with a DNS record. Its data covers only mail sent to personal Gmail accounts.
• Step 3, start low: send a small number of messages a day to engaged recipients, as Google advises.
• Step 4, stay steady: send at a consistent rate and avoid bursts or sudden doubling.
• Step 5, watch signals: Google asks for a user-reported spam rate below 0.10% and never reaching 0.30%. If bounces or deferrals start, cut volume until errors fall, then raise it again slowly.
• Step 6, keep going: hold a steady cadence after the ramp. Mailgun and the Warmy help center both describe reputation as something maintained continuously, not earned once.

How long does warming up take? The sources disagree

Google gives no fixed duration. It says the pace depends on how much you send, how often you send and how recipients respond. Vendor pages give rules of thumb, and they differ:

• Warmy calculator page: 20 to 50 real emails a day at the start, raised step by step over four to eight weeks.
• Warmy help center: at least two months for a brand-new domain. The warm-up product page FAQ says typically a week to a month.
• MailReach: 5 to 10 plain-text emails a day at first, then 15 to 25 on days 6 to 10, 30 to 50 on days 11 to 14 and 75 to 100 on days 15 to 21 for Google Workspace or Outlook senders. These are MailReach's numbers, not a Google or Microsoft rule.
• Instantly: no fixed countdown. Its slow ramp starts at 2 warm-up emails on day one and 4 on day two, and its dashboard says when an account is ready.

What to send and to whom

Send real mail to people who expect it. Google says mail from an address in the recipient's contacts is less likely to be marked as spam, and it advises against buying email addresses or sending to people who did not sign up. Yahoo advises watching bounces and inactive recipients, Microsoft advises removing invalid addresses regularly, and both ask for an easy way to unsubscribe. Keep the early messages plain and consistent with what you plan to send later, because the mail you send while warming is the picture providers form of you.

Senders of 5,000 or more messages a day to Gmail also need one-click unsubscribe on marketing mail, and Gmail counts bulk sender status per primary domain, permanently.

Do you need a warm-up tool?

A manual ramp costs time. A network tool such as the ones in the best email warmup tools automates engagement from other mailboxes. MailReach says manual warm-up works for low-volume sending but is hard to scale across many inboxes, and that senders who have stayed under about 20 cold emails a day per inbox might not need warm-up. Mailgun argued on July 20, 2026 that network engagement does not reflect your real audience and that providers are getting better at spotting it. The Google and Yahoo pages read here do not mention warm-up services.

If you want one, the Warmy review covers what that service includes and its terms.

When warm-up will not help

• Failing authentication: Warmy's calculator page says warm-up emails will not get through when SPF, DKIM or DMARC fail, and extra volume can prolong a block.
• A high spam rate: Google says bulk senders above 0.30% are ineligible for delivery mitigation until they stay below it for 7 consecutive days.
• Unwanted recipients: Google says mail to people who did not sign up draws spam reports, and over time user spam reports can lower your domain's reputation.
• Changing rules: Google's FAQ says that from November 2025 Gmail is ramping up enforcement, with an accelerated timetable for domains it classes as new. Microsoft's post, dated April 2, 2025 and updated April 30, 2025, says Outlook.com consumer mail from high-volume domains that fail SPF, DKIM or DMARC goes to Junk, with rejection to follow on a date to be announced.

Check before you scale

Before raising volume, confirm three things. Open a delivered test message and check that the headers show SPF, DKIM and DMARC passing. Look at Postmaster Tools for spam rate and authentication. Send to a few mailboxes at different providers and see where the mail lands. DMARC itself is defined in RFC 7489, which lets a domain owner ask receivers to take no action, treat failing mail as suspicious or reject it. Microsoft's post advises moving gradually from none to quarantine to reject.