Warm up your mailbox using Warmupinbox

Warmupinbox prepares your mailbox to send messages in bulk via its "mail warming" solution. The software simulates interactions between your email address and others to increase its reputation.

Michel Lieben

MAR 17 2026

Warmupinbox is very useful when you plan to send cold email campaigns using a new mailbox. Emailing platforms are wary of new email addresses. Many of them are created for the purpose of spamming, so you need to send positive signals to avoid being mistaken for a spammer.

When you create a new e-mail address (and even for an address that has already existed for a long time), it is essential to warm it up. There are several software that allow you to "warm up" your mailbox.

One such mail warming solution is Warmupinbox. The software contains a database of 10,000+ email addresses and simulates interactions between them. The aim is to convince the mail platforms that you are not a spammer. Warmupinbox will receive and send emails on your behalf. When you start prospecting, your mailbox will already have reached a certain level of trust. Your mails will land in the main inboxes and not in the "spam" or "promotions" folders.

The software is quite easy to use. Once you are registered and logged in, you will be shown the following dashboard:

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When you click on "Add Inbox" you will see the menu below:

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Vous serez invité, entres autres, à renseigner votre Email Provider. Dans le cas où vous utilisez Google, il faudra configurer vos paramètres SMTP avant de poursuivre.

Le SMTP (Simple Mail Transfer Protocol) c’est simplement un serveur qui va permettre l’envoi des mails. La configuration se fait assez rapidement. Pour commencer vous allez devoir, à l’aide de l’accès administrateur de votre boîte mail, “autoriser l’accès aux applications moins autorisées” sur votre compte.

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Suivez cet URL: https://admin.google.com/ac/security/lsa

Vous devriez tomber sur une page similaire à celle-ci:

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Cliquez sur “Autoriser les utilisateurs à gérer leur accès aux applications moins sécurisées” puis “Enregistrer”

Il faut ensuite sélectionner la boite mail spécifique que vous cherchez à synchroniser avec “Warmupinbox”.

Pour ce faire, rendez-vous ici: https://myaccount.google.com/lesssecureapps?pli=1. Une fois sur la page, activez le paramètre “Autoriser les applications moins sécurisées” en cochant le bouton comme suit:

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Enfin, il faut activer l’IMAP au sein de votre boite mail. Recherchez l’icône “Paramètres” (en haut à droite lorsque vous affichez vos mails). Puis cliquez sur “Afficher tous les paramètres”

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Dans l’onglet “Transfert et POP/IMAP” des paramètres, cochez “Activer IMAP” et enregistrez les modifications.

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Vous pouvez finalement revenir à Warmupinbox, renseigner vos informations et cliquer sur “Save”. En ce qui concerne les valeurs à indiquer, je vous conseille de suivre les recommandations de Warmupinbox.

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Michel Lieben

Founder, CEO

Michel Lieben is the Founder & CEO of ColdIQ, a B2B sales prospecting agency trusted by 100+ organizations. He’s launched hundreds of outbound campaigns, mastered tools like Clay and Lemlist, and shares sharp, actionable insights on scaling sales with AI, automation, and strategy.

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FAQ

What is the typical timeframe to see results after starting mailbox warm-up?

Results vary, but noticeable improvements often appear within 1-2 weeks. Some emails may still land in promotions or spam initially as reputation builds gradually. Consistent daily sending and receiving help speed up the process.

How many emails should I send daily during warm-up?

Start with a small number like 10-20 emails per day and gradually increase. This prevents sudden spikes that may trigger spam filters. Warmupinbox automatically scales volume for you based on best practices to maintain natural sending behavior.

Can I use Warmupinbox with any email provider or only Gmail?

Warmupinbox supports most major providers like Gmail, Outlook, and custom domains that use standard SMTP and IMAP protocols. However, some setup steps may differ depending on your email service. Check your provider’s documentation for enabling SMTP/IMAP access if needed.

Is it safe to allow less secure app access in Gmail for mailbox warm-up?

Enabling less secure app access provides necessary permissions to Warmupinbox to send emails via SMTP. While it lowers some account defenses temporarily, the risk is minimal if you follow additional security best practices like two-factor authentication and regularly monitoring account activity.

What happens if I stop using Warmupinbox after the warm-up period?

Once your mailbox gains a good reputation, you can stop warm-up without issues. However, stopping abruptly after high sending volumes can cause deliverability drops. It’s better to gradually taper sending or maintain consistent, moderate email activity to keep reputation stable.

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Michel Lieben