What is Email Warmup?

Email warmup is the process in which a new email domain or address gradually builds up its sending volume to establish a good sender reputation with email providers. Without warmup, emails from new domains almost certainly end up in the spam folder, regardless of the quality of the content.

How does email warmup work?

During warmup you send a limited, gradually growing number of emails every day. Start with 10 to 20 a day and increase weekly. Warmup tools such as Smartlead, Instantly or Mailreach automate this by sending emails and simulating positive interactions, so mail servers learn to see the domain as trustworthy.

Why is warmup so important?

Email providers such as Gmail and Outlook do not trust new domains by default. By building volume gradually with good open rates and low spam scores, you build domain reputation. This is the absolute basis of good deliverability.

Warmup for cold email

For cold email campaigns, always warm up for at least 4 weeks before you start outreach. Use several domains to spread volume and limit risk.

How long does email warmup take?

At least 3 to 4 weeks for a basic reputation. For high sending volumes, 6 to 8 weeks for optimal deliverability.

Can I warm up a domain manually?

Yes, but automated warmup tools are more consistent and more effective. More at developers.google.com/search.