TL;DR: Use this guide to choose the right inbox to connect to lemwarm and understand what lemwarm can actually warm up. This helps you avoid setup mistakes that can hurt deliverability or stop the warm-up from working as expected. Takes about 3 minutes.

If you're setting up lemwarm for the first time, this article will help you confirm whether your email address, alias, domain, or provider is supported.

If you already connected a supported inbox and only need advanced troubleshooting, this article may not be the right one.

Connecting the right inbox is one of the most important parts of getting started with lemwarm. If you try to warm an unsupported setup, such as an SMTP relay or a masked alias, the warm-up will not work the way you expect.

Using the correct email setup also helps protect your email deliverability and supports better inbox placement over time.

Before you connect an inbox, decide whether you are warming a real mailbox with its own inbox access, or just a sending alias.

1. Confirm that you want to warm an email address, not an IP.

lemwarm is designed to warm up a mailbox. It does not warm up dedicated IPs or shared IP infrastructure.

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2. Check whether the inbox is part of a shared domain.

If you warm email addresses on a domain and follow good deliverability practices, your domain reputation can benefit. If other users on the same domain send poor-quality campaigns, they can still damage that reputation.

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3. Verify whether the address is a primary inbox or an alias.

If the address has its own inbox, you can warm it. If the address is only a mask that forwards to another mailbox and does not have its own inbox, you cannot warm it with lemwarm.

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4. Make sure the address is the primary email on the provider side.

lemwarm warms the email address defined as the primary email in your email provider account. If you want to warm multiple inboxes, each inbox must be connected separately.

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5. Add separate seats if you want to warm multiple mailboxes.

For example, if you connect [email protected] and that mailbox has aliases like [email protected] and [email protected], lemwarm will warm [email protected]. To warm [email protected] or [email protected], you need additional seats and must connect those inboxes individually.

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6. Check that your provider supports both SMTP and IMAP inbox access.

lemwarm requires a connection to a single inbox with both SMTP and IMAP. If your setup uses an SMTP relay instead of a real mailbox, it is not supported.

✓ You connected a real mailbox, not an SMTP relay

✓ The connected address is the primary email on the provider side

✓ The mailbox has its own inbox access if you are using an alias

✓ You understand which inbox lemwarm is warming and whether you need additional seats for other addresses

Primary mailbox

This is the simplest and recommended setup. lemwarm warms the connected primary inbox directly.

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Alias with its own inbox

This can be warmed, as long as the alias is a real mailbox with inbox access.

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Alias without its own inbox

This cannot be warmed. If the alias is only forwarding mail and does not have its own mailbox, lemwarm cannot use it.

Issue: I connected an alias, but the wrong address is being warmed

Root cause: The alias is not the primary email address on the provider side

Fix:

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Issue: I want to warm my entire domain

Root cause: lemwarm warms individual email addresses, not the whole domain directly

Fix:

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Issue: My SMTP relay or sending service will not connect

Root cause: lemwarm requires one mailbox with both SMTP and IMAP access, not a relay or sending-only service

Fix:

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Issue: I expected all aliases to warm automatically

Root cause: lemwarm warms the connected primary mailbox unless other inboxes are connected separately

Fix:

Here is a non-exhaustive list of providers and services that are not supported as SMTP relay connections: