Email Warmup
The process of gradually increasing email sending volume on a new domain or mailbox to build sender reputation with email providers.
What is Email Warmup?
Email warmup is the process of gradually ramping up sending volume on a new email account or domain to establish a positive sender reputation with mailbox providers like Google, Microsoft, and Yahoo. New mailboxes have no sending history, which means providers have no basis to trust them. Sending a large volume of email from an unknown account triggers spam filters and can get the account suspended or blacklisted. Warmup solves this by mimicking the natural sending patterns of a legitimate user over a period of weeks.
How Warmup Works
During the warmup period, emails are sent in small, incrementally increasing batches. In the first few days, a new account might send only five to ten messages. Over the course of two to four weeks, that number gradually climbs to the target daily volume. The key is not just sending but also generating positive engagement signals. Warmup tools automate this by sending emails between a network of real inboxes, where the messages are opened, read, replied to, and removed from spam if they land there. These interactions tell email providers that recipients find the sender’s messages valuable.
Why Warmup Matters
Skipping warmup is one of the most common mistakes in cold email. Without it, even perfectly written emails with valid DNS authentication will land in spam. Email providers track sending patterns at the account and domain level. A sudden burst of outbound messages from a mailbox with no history is a strong negative signal. Warmup establishes the baseline pattern that providers expect from a real, active email user.
Warmup Duration and Strategy
A standard warmup period runs two to four weeks, though the exact timeline depends on your target daily volume and the provider. Google Workspace accounts tend to be more sensitive than Microsoft 365 accounts and may require a more conservative ramp. During warmup, avoid sending any cold outreach. Use the warmup period exclusively to build reputation. Once the account is warmed, transition to live sending while keeping warmup running in the background at a reduced level to maintain engagement signals.
Outspun & Email Warmup
Outspun’s warmup service automates the entire warmup process — gradual volume ramp, real engagement signals, and ongoing maintenance warmup. Warmup is included in every managed plan and also available as a standalone service for teams that bring their own domains.
Keep learning
IP Reputation
A score assigned to an IP address by mailbox providers based on its historical sending behavior, complaint rates, and engagement patterns.
Inbox Placement
The percentage of sent emails that successfully land in the recipient's primary inbox rather than the spam folder, promotions tab, or being rejected entirely.
Need help with Email Warmup?
Outspun handles it for you. Managed email infrastructure with everything configured and monitored.