Key takeaway: Connecting Frostmailer inboxes to Instantly is a straightforward IMAP and SMTP connection. The three settings people get wrong: the daily send limit, the custom tracking domain, and connecting SMTP without IMAP so replies vanish.

Connecting your Frostmailer inboxes to Instantly is a straightforward IMAP and SMTP connection. Here is the flow, plus the settings people get wrong.

Before you start, have your inbox credentials ready: the email address, password (or app password), and the IMAP and SMTP server details for your mailbox type. Google, Microsoft, and SMTP mailboxes each have their own server settings, so make sure you are using the right set.

Step 1: Add your accounts

In Instantly, go to Email Accounts and choose to add an account. You will pick your provider type. Google Workspace and Microsoft accounts often connect via OAuth (simplest: you authorize and it is done). SMTP mailboxes connect by entering server details manually.

Step 2: Enter SMTP and IMAP details (for manual connections)

You will need the SMTP host and port for sending, the IMAP host and port for reading replies, and your credentials. Both must be configured. SMTP alone means you send but never see replies.

Step 3: Bulk import if you have many inboxes

Instantly supports adding accounts in bulk via CSV, which matters a lot when you are connecting dozens. Format the sheet with one row per inbox and the required credential columns, then upload rather than adding them one at a time.

Step 4: Enable warm-up

Turn on warm-up for each account. If your inboxes came pre-warmed, still leave warm-up running at a low level permanently. It maintains the engagement signal alongside real campaigns.

Step 5: Set your sending limits

This is the setting that saves or destroys you. Cap each inbox to a conservative, provider specific number: 2 to 3 a day on Azure, up to 15 a day on Google. Set a minimum delay between emails and enable randomization so your sending does not look mechanical. Do not accept a high default.

Step 6: Connect your custom tracking domain

In settings, add your tracking domain (a CNAME subdomain you own) rather than using the shared default, otherwise you inherit other users' tracking reputation. Or disable open tracking entirely and measure replies.

Step 7: Test before you launch

Send a test to a seed inbox on Gmail and Outlook. Confirm it arrives, check placement (primary versus promotions versus spam), and confirm a reply flows back into the unibox. Only then point a real campaign at it.

The three mistakes to avoid: accepting the default daily send limit, skipping the custom tracking domain, and connecting SMTP without IMAP so replies vanish. Fix those three and the rest is routine. Frostmailer inboxes arrive with the credentials and tracking subdomain ready to plug straight into Instantly.

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