When a campaign is ready to leave Draft, you have two choices: send it right away, or schedule it for a future date and time. Either way, the campaign moves through the same lifecycle fromDocumentation Index
Fetch the complete documentation index at: https://docs.lettr.com/llms.txt
Use this file to discover all available pages before exploring further.
Preparing to Sent — only the trigger differs.
This page covers each transition in detail, what you can and can’t change at each step, and what to expect once a send is in progress.
The Campaign Lifecycle
| Status | Reachable from | Editable? | What’s happening |
|---|---|---|---|
| Draft | New campaign | Yes — everything | You’re still composing |
| Scheduled | Draft (you set a future time) | No (unschedule first) | Waiting for the scheduled send time |
| Preparing | Draft (send now) or Scheduled (time reached) | No | Recipients being resolved, content being validated |
| In review | Preparing (rarely) | No | An automated check flagged the content; a Lettr admin is reviewing |
| Sending | Preparing (passed validation) | No | Emails being delivered in batches |
| Sent | Sending (completed) | No (read-only) | All recipients processed; analytics still updating |
| Failed | Preparing (no recipients or unexpected error) | No | Campaign couldn’t be sent |
- Once a campaign leaves Draft, you can’t edit it. Scheduled campaigns can be moved back to Draft (unschedule), but everything else is locked in.
- Once a campaign enters Preparing, it cannot be stopped. There is no in-flight cancellation. If you realize a campaign has a problem after you press Send, your options are limited to (a) letting it complete and following up with a correction or (b) for a scheduled campaign that hasn’t started yet, unscheduling before the send time arrives.
Sending a Campaign Immediately
From the Review step of the builder, click Send now. What happens:- Lettr validates the campaign has the required content (subject, from address, body)
- The campaign moves to
Preparingand starts resolving recipients - Once recipients are resolved and the content is checked, the campaign moves to
Sendingand emails start going out in batches - When every recipient has been processed, the campaign moves to
Sent
Scheduling for Later
In the Schedule step of the builder, choose Schedule and pick a date and time. The campaign moves toScheduled and waits.
How Times Are Interpreted
When you pick a time in the schedule picker, Lettr interprets it in your browser’s local timezone. The picker shows you the time in your local zone so you don’t have to do timezone math.All recipients receive the email at the same wall-clock moment — there is no per-recipient timezone scheduling (sometimes called “send at 9am in each recipient’s local time”). The scheduled time is a single global event.
When the Schedule Fires
Lettr checks every minute for campaigns whose scheduled time has been reached. When yours is up, the campaign automatically moves fromScheduled to Preparing and follows the same flow as a “Send now” campaign from there.
There can be a brief delay (typically a few seconds, up to a minute) between the scheduled time and when sending actually begins. This isn’t a precision-down-to-the-second mechanism — schedule a few minutes before any hard deadline, not exactly at it.
Unscheduling
If you want to make changes to aScheduled campaign — or cancel the send entirely — you can unschedule it from the campaign’s edit page. Unscheduling:
- Moves the campaign back to
Draft - Clears the scheduled time
- Re-opens all fields for editing
The Preparing State
When a campaign entersPreparing, Lettr is doing two things behind the scenes:
- Resolving recipients. The audience selection (lists, segments, all contacts) is evaluated and all eligible
subscribedcontacts are written to a per-campaign recipient list. Lettr deduplicates contacts who match multiple sources and filters out non-subscribed contacts. - Running a content check. A safety check inspects the campaign content for signals of high-risk sends (unusual patterns, unverified domains under heavy use, etc.). Most campaigns clear this check immediately.
If No Recipients Match
If the resolved recipient list is empty (for example, you selected a segment that no contacts currently match), the campaign moves toFailed rather than Sending. The Show page tells you the cause so you can adjust the audience and try again.
The “In Review” State
If the content check flags the campaign, the status moves fromPreparing to In review and pauses there until a Lettr admin manually approves it. This is rare in practice — most campaigns pass the check automatically — and is intended to catch unusual cases (for example, a brand-new account sending a very large campaign for the first time, or content patterns that strongly resemble known abusive sends).
If your campaign lands in review, you’ll see a status indicator on the Show page. Contact support@lettr.com if it remains in review longer than you’d expect.
The Sending State
Once a campaign isSending, emails are delivered to recipients in batches. Lettr handles the queueing automatically — you don’t configure batch sizes or throughput.
Progress is visible on the Show page in real time:
- A progress bar shows
recipients sent / total recipients - The page polls every few seconds and updates automatically
- Engagement metrics (opens, clicks) start populating as recipients interact
Send Speed
There is no fixed sending rate. Lettr dispatches each batch as soon as the previous one completes, so the practical send speed depends on the size of the recipient list. Even very large campaigns typically complete within minutes to an hour, not days. There is no “quiet hours” or send-window configuration. Once you start sending, the campaign goes out as quickly as the queue allows.The Sent State
When every recipient has been processed, the campaign reachesSent. From here on:
- The campaign content is read-only. You cannot edit anything.
- Engagement metrics keep updating as recipients continue to open and click. Most opens happen within the first few hours, but the long tail of engagement can run for days.
- The per-event activity feed records every individual delivery, open, click, bounce, complaint, and unsubscribe. This data is available for 30 days; after that it’s archived to a downloadable file.
Failed Campaigns
A campaign can fail at the Preparing step if:- No subscribed contacts match the selected audience
- An unexpected error occurs during recipient resolution or content validation
Failed campaign cannot be retried directly — instead, duplicate it, fix the issue (typically by adjusting the audience selection), and send the duplicate.
You can delete failed campaigns from the Campaigns list.
What You Cannot Do
Knowing the limits up front saves frustration during sends:| Want to | Possible? | Workaround |
|---|---|---|
Stop a campaign that’s in Preparing or Sending | No | Wait for it to complete; follow up with a correction campaign |
| Edit a campaign after sending | No | Duplicate and re-send |
| Schedule per-recipient timezone sends | No | Schedule different campaigns per timezone, or accept one global send time |
| Pause an in-progress send and resume it later | No | Wait for completion |
| Recover a deleted campaign | No | Deletion is permanent (only Draft and Failed campaigns can be deleted) |
Next Steps
Analytics & Reporting
Track engagement after the campaign sends
Audience Selection
Refine who receives your campaign
Best Practices
Deliverability and sender-reputation guidance