Why You Need to Warm Up Cold Email Inboxes

A normal inbox, like the one you use at work, has a history. It sends and receives emails every day, has two-way conversations and rarely gets spam complaints. Mailbox providers trust it.

A brand new cold email inbox has no history. If it suddenly starts sending dozens of emails a day to strangers, Gmail and Outlook treat it as suspicious and send its emails to spam.

SPF, DKIM and DMARC prove your emails come from you, but they don't prove you are a good sender. That needs a reputation, which takes time to build.

What warmup does

Email warmup is an automated process that builds that reputation. A warmup service such as Instantly connects your inbox to a large network of other real inboxes. It then:

• Sends a small number of normal-looking emails from your inbox, increasing slowly each day
• Opens and replies to them from other inboxes in the network
• Moves them out of spam and marks them as important if they land there

To mailbox providers, your inbox looks like it is being used by a real person who gets replies.

How long to warm up

Minimum warmup before your first campaign	14 days
Safer target	30 days
After you start sending	Keep warmup running all the time, alongside your campaigns

Use the warmup period to find and validate your leads and write your emails.