1. Send time – a campaign only starts once its Scheduled for time has passed; check the campaign page.
2. Onboarding – if the sending domain's link validation was never completed, the background sender skips every message for your account. Open /admin/marketingcampaigns/onboarding and confirm step 3 shows All done.
3. Errors – look at the Error tab and open the campaign; a red box This campaign could not be sent due to the following error(s) lists the provider's message (for example an invalid sending address or a suspended sending account). Messages that failed three times are not retried.
4. Plan / overdue invoice – flows stop queueing when the monthly limit is reached, and an overdue Sprwt invoice blocks new campaigns.
5. Batch sending – large campaigns are sent in batches of up to 50 per run of the background job, so Outbox progress (sent/total) is normal for big audiences.

If the campaign shows no errors, its time has passed and the count does not move for a long time, contact Sprwt support – the server-side sending job may not be running.