How to Warm Up a New Email Account for Bulk Sending (Day-by-Day Plan)

A brand-new email account that suddenly sends 1,000 emails looks exactly like a spammer’s account, even if your list is perfect. Email providers judge senders by their history, and a new mailbox or domain has none. Warming up builds that history gradually so Gmail, Outlook and Yahoo learn to trust you.

What is email warm-up?

Email warm-up means starting with a small number of emails per day and increasing slowly over several weeks. During that time, receiving servers watch how people react: opens, replies, “not spam” clicks, bounces and complaints. Good reactions build a positive sender reputation; bad ones damage it quickly.

You need to warm up:

• New mailboxes (a new Gmail, Google Workspace or Microsoft 365 account).
• New domains, even if the mailbox software is old.
• New dedicated IP addresses at an email service.
• Accounts that have been quiet for months.

Before you start

1. Authenticate your domain with SPF, DKIM and DMARC (setup guide).
2. Use a real signature, profile photo and a real From name.
3. Clean your list. Bounces during warm-up hurt the most. Verify every address first.
4. Start with your best contacts: people who know you and are likely to open and reply.

A 4-week warm-up schedule

These numbers are for one mailbox. If any warning sign appears (below), hold the same volume for a few days or go back a step.

Week	Emails per day	Who to send to
Week 1	10–20, rising to about 40	Colleagues, existing customers, people who reply
Week 2	40–100	Engaged contacts who opened recently
Week 3	100–200	Your wider opted-in list
Week 4	200–400	Normal campaigns, still well under the provider’s limit

Google Workspace allows about 2,000 messages a day, but healthy bulk sending from one mailbox usually stays far below that. For more volume, warm up several mailboxes in parallel and rotate between them instead of pushing one account to its limit.

Sending habits during warm-up

• Spread emails through the day. Use a delay of 30 seconds or more between emails, with random jitter.
• Personalise. Emails that look personal get replies, the strongest positive signal.
• Keep it light. Few links, no attachments and simple formatting while the account is new.
• Reply to replies. Real conversations tell providers the account belongs to a real person.
• Keep the same pattern every day. Steady volume looks natural; spikes don’t.

Warning signs: slow down if you see these

• Bounce rate above 2%. Your list needs cleaning.
• Spam complaints, or Gmail Postmaster Tools showing a spam rate near 0.3%.
• Test emails landing in spam at Gmail or Outlook.
• SMTP errors such as “daily sending limit exceeded” or temporary rejections (421 or 4xx codes).

When you see one, keep volume flat or reduce it, fix the cause and only increase again once results are good.

Warm-up with HAAN MAIL PRO

HAAN MAIL PRO makes a steady warm-up easy:

• Delay and random jitter between emails, and batches with pauses.
• Scheduling, so a campaign can go out at the same time each day.
• SMTP pool rotation: add each new mailbox to the pool and campaigns share the volume between them. The pool shows real sent counts and success rates per account, so you can spot a struggling account early.
• Verify MX and automatic duplicate removal to keep bounces low.

See the user guide to set up the SMTP pool, and how to send bulk email with Gmail for Gmail-specific limits.

After warm-up

Warm-up isn’t one-off. Keep sending at a consistent volume, remove addresses that bounce or never engage, and increase gradually whenever you need more capacity. If you stop sending for a month or more, warm up again before a large campaign.