Diagnose in this order
1. Check the Outbox
Open Outbox and look at the tabs: Scheduled, Processing, Sent.
- Emails sitting in Scheduled with due times in the past → sending is blocked, continue below.
- Emails moving through Processing → it's working, just slower than expected.
2. Check the sending window
Emails due outside the campaign's Sending Windows wait for the next window. A campaign with a narrow window and a paused-today schedule can look "stuck" while behaving correctly.
3. Check the campaign state
Filter the campaign list by Status = Paused. A paused campaign holds all sends. Resume it and watch the Outbox.
4. Check the Daily Sending Limit
The mailbox-level Daily Sending Limit (Settings → Mailbox) caps sends across all campaigns. If the limit was hit, additional emails wait until the next day. Multiple campaigns on one mailbox make this cap easier to hit than expected.
5. Check Daily Prospect Start
Prospects enter campaigns at the campaign's Daily Prospect Start rate (default 50). If it's set to 5, the campaign moves five new prospects per day — by design.
6. Check the mailbox connection
A disconnected or expired mailbox connection halts sends from it. Reconnect under Settings → Mailbox — see Mailbox connection problems.
Still stuck?
Gather: the campaign name, an affected prospect, and Outbox screenshots of the stuck emails. That's everything support needs.