On the Warming page, click "Import External". Download the CSV template, fill in one row per mailbox (email, name, password, provider, and for custom SMTP the SMTP/IMAP host and port), and upload it. Review the preview, pick daily volume and ramp speed, and click "Import & Enable Warming". Use an app password, never your main account password. Imported mailboxes warm at $0.60 per mailbox per month, the same as Winnr mailboxes, and you don't need a Winnr plan to use this.
When external warming makes sense
- Rescuing a throttled Google Workspace inbox. A few weeks of warming can help rebuild its sending reputation.
- Warming an inbox for high-touch outreach. Some reps prefer a Google Workspace or Microsoft 365 inbox for personal outreach. Warming gets it ready to send.
- Trying Winnr's warming on infrastructure you already have, before moving mailboxes to Winnr.
When it doesn't make sense
- Bulk cold campaigns. Google Workspace and Microsoft 365 throttle outbound heavily. For volume, Winnr mailboxes are cheaper and built for it.
- Cost. A Workspace or 365 seat plus $0.60 for warming costs more per mailbox than a Winnr mailbox, which works out to about $1.38 per mailbox per month on the Startup plan before warming, or about $1.98 with warming.
What's next
Step-by-step
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1. Create app passwords
Gmail / Google Workspace: turn on 2-Step Verification, then create an app password at myaccount.google.com/apppasswords. Microsoft 365 / Outlook: use an app password; your Microsoft admin has to allow app passwords first. Custom SMTP: use the mailbox's normal SMTP/IMAP password and server details.
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2. Open Import External
App sidebar → Warming → Import External (top right). If nothing is warming yet, use the "Import External Accounts" button on the intro screen.
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3. Fill in the CSV
Click Download CSV Template. Columns are email, name, password, provider, smtp_host, smtp_port, imap_host, imap_port. Provider is google, microsoft or smtp. For google and microsoft you can leave the host and port columns empty; Winnr fills in the standard settings. For smtp, the SMTP and IMAP hosts are required.
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4. Upload and review
Drag the file into the dialog or click Browse Files. The preview flags rows with problems (bad email format, missing password, unknown provider). Addresses already on your account are skipped as duplicates.
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5. Choose settings and import
Set Target emails/day (1 to 20) and Ramp-up speed, check the cost summary ($0.60 × mailboxes per month), and click "Import & Enable Warming (N)". The first month is charged right away; if the payment fails, nothing is imported. Progress shows as each batch is processed.
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6. Watch the mailboxes
Imported mailboxes appear on the Warming page with a Google, Microsoft or External badge. Use the All / Winnr / External toggle above the Mailboxes table to filter to them.
Frequently asked questions
Do I need a Winnr plan to warm external mailboxes?
No. If you don't have a Startup or Enterprise plan, warming is billed on its own monthly subscription at $0.60 per mailbox. See [Warming billing](/help/warming/warming-billing.html).
Do imported mailboxes count against my plan's mailbox limit?
No. External mailboxes are warming-only. They don't use a mailbox slot and they don't appear on the Email Users page, only on the Warming page.
Does Winnr send from my external mailbox?
Yes. Warmup emails are sent and received with the credentials you provide, which is how the mailbox builds reputation. Your real cold campaigns are separate and run through your sending tool.
Is it safe to give Winnr my Gmail password?
Never use your main account password. Create an app password and use that. App passwords are single-purpose and can be revoked at any time without affecting your normal login. The same applies to Microsoft and other providers.
What SMTP/IMAP settings does Winnr use for Gmail?
SMTP smtp.gmail.com port 465, IMAP imap.gmail.com port 993, username = full email address, password = app password. Winnr fills these in when provider is google.
What settings does Winnr use for Microsoft 365 / Outlook?
SMTP smtp.office365.com port 587, IMAP outlook.office365.com port 993, username = full email address, password = app password. Winnr fills these in when provider is microsoft.
A mailbox shows Problem. What's wrong?
Winnr couldn't sign in to it. The usual causes are a wrong or revoked app password, app passwords not being allowed on the account, or IMAP being turned off at the provider. Fix it at the provider, then delete the mailbox from the Warming page and import it again with the correct details. If it still shows Problem, contact support@winnr.app.
How do I remove an external mailbox?
On the Warming page, open the "..." menu on its row and choose Delete Account. Warming stops and the mailbox is removed from Winnr. Your actual Gmail or Outlook mailbox is untouched.
How many can I import at once?
There's no practical limit in the dialog; large files are processed in small batches with a progress counter. Through the API, one request accepts up to 200 accounts.