What is email warmup and why is it essential for cold email?

Email warmup is the process of establishing sender reputation before conducting actual campaigns. For cold email, it's essential because you're starting with no positive history.

What warmup accomplishes: Mailbox providers observe sending patterns and engagement over time. Warmup creates a baseline of normal behavior and positive signals that help future messages get delivered.

Why cold email needs it: Cold campaigns generate lower engagement and higher complaints than permission-based email. Without established reputation, mailbox providers have no reason to trust your messages. You're competing against spam from unknown senders.

How warmup works: Send small volumes to recipients who will engage positively. Gradually increase volume while maintaining engagement quality. The goal is demonstrating that recipients want your email before scaling to audiences who might not.

Consequences of skipping: Sending high volume from a new domain triggers immediate suspicion. Messages land in spam, engagement suffers, and reputation damage accumulates before you've even started real campaigns.

Warmup is an investment in future deliverability. No experienced captain sets sail without first checking the vessel.