Email Warmup

What is Email Warmup?

Email warmup is the process of gradually increasing your sending volume on a new IP address or domain to build a positive reputation with mailbox providers. Instead of blasting thousands of emails at once, you start small and grow steadily, showing ISPs that you’re a legitimate sender.

Why it matters

ISPs are suspicious of new IPs or domains that suddenly start sending high volumes. Without warmup, your emails may be blocked, throttled, or routed to spam. Warmup helps establish trust and improves long-term Deliverability.

How it works

You begin by sending small batches (50–100 emails) to your most engaged users—the ones most likely to open and click. As engagement signals accumulate, ISPs “learn” that your emails are wanted. Over 2–4 weeks, you gradually scale volume until you reach your target sending levels. AutoSend automates this process, ensuring the right pacing and monitoring responses from providers.

Examples

• A SaaS startup moving from a shared IP to a dedicated one and warming it before product launch.

• A brand switching ESPs and needing to re-establish trust with Gmail and Outlook.

• A new domain sending limited campaigns before scaling to full volume.

Best practices

• Start with highly engaged contacts to maximize positive signals.

• Scale gradually—doubling every few days is safer than big jumps.

• Monitor bounce and complaint rates closely during warmup.

• Keep content clean and consistent—don’t experiment with spammy subject lines during warmup.

Related terms

Dedicated IP vs Shared IP, Email Deliverability, Blocked Emails

FAQs

How long does warmup take?
Typically 2–4 weeks, depending on your target volume. Larger senders may need more time, but rushing the process increases the risk of blocks and spam placement.

Do I need to warm up a shared IP?
No. Shared IPs are managed by your ESP, which spreads reputation across multiple senders. Warmup only applies to dedicated IPs or new domains.

What happens if I skip warmup?
Skipping warmup is risky. ISPs may treat your emails as suspicious, leading to widespread blocking or spam folder placement. Recovering from a bad start often takes longer than doing a proper warmup from the beginning.