The usual causes: the draft is held for review, the agent hit its daily budget, the mailbox isn't healthy, credits ran out, or the contact is suppressed. Check the Agent Timeline — it records the exact reason for every action not taken.
Check the timeline first
Open Agents → Timeline for the account. Every skipped or held send is logged with a reason. This almost always tells you the answer directly, so start here before changing settings.
Common causes
The draft is held for review and waiting on approval (see Review and approve agent drafts); the agent hit its daily account budget and queued the rest for tomorrow; the mailbox is Warming or Unhealthy (see Mailbox health badges explained); send credits are exhausted (see Credits and usage); or the contact is on a suppression list or opted out.
Fixes
Approve held drafts in Agents → Drafts, raise the daily budget if the queue is backing up, wait for the mailbox to reach Health: Good, top up or upgrade for more credits, and confirm the contact isn't suppressed. Resolve the specific reason the timeline names.
If the timeline shows a send but nothing arrived
That's a deliverability issue, not a sending issue — the email left but didn't land (see Monitor sender reputation). Check bounce logs and mailbox health, and verify the recipient address was valid.
