IP warm-up - What, How and Why

If you manage your own email delivery—whether through your own SMTP servers or a mix of third party providers—understanding IP warm-up can make a real difference in how consistently your messages reach inboxes.

When you control your infrastructure, you also control your reputation. That’s powerful, and nuevoMailer gives you the tools to manage it with confidence.

What Is IP warm-up and why it matters

IP warm-up is the process of gradually increasing the volume of emails sent from a new or previously inactive IP address.

Mailbox providers (Gmail, Outlook, Yahoo, corporate servers, etc.) watch how an IP behaves. If they suddenly see a large spike in volume from an unknown source, they may treat it as suspicious. That can lead to throttling, deferrals, or landing in the spam folder.

• Build a positive sending reputation
• Demonstrate consistent, predictable behavior
• Reduce the risk of blocks or spam filtering
• Improve long term deliverability and inbox placement

If you’re using your own SMTP servers, this process is essential. You’re the one establishing the reputation, and mailbox providers will judge your IP based on how you introduce it.

When is IP warm-up necessary?

• You’re using a new SMTP server with a fresh IP
• You’re returning to an IP that has been inactive for weeks or months
• You’re switching from a shared IP to a dedicated IP
• You’re scaling up your sending volume and want to avoid sudden spikes
• You’re migrating from another platform and want a clean, reputation safe transition

If you’re using third party email service providers like Amazon SES, Mailgun, or similar, the warm-up process may be handled for you, especially if you’re on shared IP pools. These providers already maintain strong reputations and manage volume ramp ups internally.

However, if you use dedicated IPs with these services, warm-up is still required. The good news is that nuevoMailer gives you all the controls you need to do it smoothly.

How to do IP warm-up with nuevoMailer

One of the strengths of nuevoMailer is the flexibility it gives you in managing sending volume. You can warm up a new SMTP server or IP address gradually and safely using built in quotas and Sender profile options.

1. Set hourly and daily quotas at the SMTP server level  
   Every SMTP server you configure in nuevoMailer has its own:
   • • Hourly quota
   • • Daily quota
2. Set hourly and daily quotas at the Sender profile level  
   Sender profiles add another layer of control. You can define:
   • • How many emails a sender profile is allowed to send per hour
   • • How many emails it can send per day
   This is especially useful when you want to manage warm-up across multiple campaigns or lists without manually adjusting each one.
3. Use multiple SMTP servers in a single Sender profile
   A powerful warm-up strategy is to mix a new SMTP server with existing, well reputed servers. For example:
   • • Add your new SMTP server to a Sender profile
   • • Assign it a very low quota
   • • Keep your mature SMTP servers active with higher quotas
   • • Enable also "Continuous SMTP rotation / Load balancing" (optionally for achieving a higher rotation rate among available SMTP servers).

   nuevoMailer will distribute the sending load according to the quotas you set.
   This means your new IP starts small while your established servers continue handling the bulk of your volume—no disruption, no risk.

4. Set daily quotas at the campaign level
   Campaign level quotas give you even more precision. You can limit how many emails a specific campaign sends per day, ensuring that even if your lists are large, your warm-up schedule stays controlled.
5. Enjoy full flexibility
   Because quotas exist at multiple layers (SMTP servers, Sender profiles, and Campaigns) you have complete freedom to design a warm-up plan that fits your infrastructure and your goals. You can:
   • • Start extremely small
   • • Increase volume gradually
   • • Spread sending across multiple servers
   • • Keep your existing delivery stable while warming up new IPs

   nuevoMailer doesn’t force a single method. It gives you options, and you choose the strategy that works best for your setup.

Additional tips for a successful warm-up

1. Send to your most engaged subscribers first. High opens and clicks build reputation faster.
   Tip: with nuevoMailer you can prioritize sending to subscribers with highest opens or clicks and do Send time optimization.
2. Avoid sending to old or unverified lists during the early stages.
3. Increase volume gradually, typically doubling every few days depending on performance.
4. Monitor bounces and complaints closely. If you see issues, slow down the ramp up.
5. Authenticate your domain (SPF, DKIM, DMARC). This is essential for reputation building.
6. Keep sending consistent, both in volume and frequency. Sudden spikes can hurt your progress.

With nuevoMailer, you’re in full control of your sending behavior, and that control is exactly what mailbox providers want to see.

Set yourself up for long term deliverability success

Warming up an IP doesn’t have to be complicated. With nuevoMailer, you already have the tools to manage it safely and effectively.

Whether you’re introducing a brand new SMTP server, scaling your infrastructure, or transitioning to dedicated IPs, you can build a strong reputation step by step.

You’re not just sending email—you’re shaping how mailbox providers perceive you. And with the right warm-up strategy, you set yourself up for long term deliverability success.

For further technical details see nuevoMailer User's guide.