Connect Lemlist to your Inboxlee mailboxes
API-key method and CSV fallback for Lemlist users. Includes daily-cap configuration and warmup notes.
Rejwan Nirob·Feb 2, 2026·4 min readLemlist is the third native integration in Inboxlee, alongside Smartlead and Instantly. The connection process is similar - one API key, one click, mailboxes flow in.
Step 1 - Lemlist API key
In Lemlist, go to Settings → API & Integrations. Generate an API key with email-account read scope. Copy it.
Step 2 - Connect in Inboxlee
Inboxlee dashboard → Integrations → Lemlist → Connect. Paste the key. Save. Live mailboxes flow into Lemlist within seconds.
Step 3 - Configure cohort sending
- Group mailboxes by domain in Lemlist for cohort sending
- Cap daily sends at 10 to 20 per mailbox for cold outbound - well below the platform ceiling
- Use Lemlist warmup with API toggle on - Inboxlee tracks the curve
- Verify reply detection is enabled - replies come back to the mailbox
If you prefer not to use API sync, export your live mailboxes from Inboxlee → Mailboxes → Export CSV and bulk-upload to Lemlist → Email Accounts → Import.
Frequently asked
How do I connect Lemlist to my Inboxlee mailboxes?
Generate an API key in Lemlist (Settings → API & Integrations, email-account read scope), then paste it in Inboxlee → Integrations → Lemlist → Connect. Live mailboxes flow into Lemlist within seconds. CSV fallback is available if you prefer not to use API sync.
What daily-send cap should I use in Lemlist for cold email?
10 to 20 emails per mailbox per day for safe cold outbound. Lemlist will let you set higher, and Workspace/M365 will technically tolerate up to ~500/day at full reputation, but partner-program telemetry shows sustained sends above 20/day correlate with placement decline - especially in the first 30 days after warmup.
Does Lemlist warmup work with Inboxlee?
Yes. Enable Lemlist warmup with the API toggle on, and Inboxlee reads the warmup-day data back via API. Your sender warms; Inboxlee tracks the curve in one dashboard alongside infrastructure health.
Do replies come back through Lemlist or to the Inboxlee mailbox?
Replies arrive at the Workspace or M365 mailbox directly (since that is the real inbox). Lemlist detects replies via IMAP and updates campaign status. Inboxlee provisions the mailbox; Lemlist runs campaigns; the inbox itself is the one source of truth.