Sending email

There are two ways email leaves mailer123: a campaign to many recipients (see Campaigns), and a single message — a test or a one-off transactional email. Both go through the same delivery guards.

What every send checks#

Before a message goes out, the app verifies:

1. Verified sender — the from address must be on a domain you've verified. Unverified senders are rejected.
2. Send quota — each send counts against your plan's daily and monthly limits (per recipient). See Send quotas.
3. Suppression — addresses that previously bounced, complained, or unsubscribed are skipped and never re-emailed. See Deliverability.
4. Reputation — if a domain's bounce or complaint rate spikes, sending can be auto-paused to protect your reputation.

Personalization tokens like {{name}} and {{unsubscribe_url}} are filled in per recipient at send time — see Personalization.

Test sends#

The quickest way to see a real email is a test send. From a campaign's Content step (or a template) click Send test to deliver a single preview to your own address before committing to a full send.

Single / transactional email#

To fire individual emails programmatically (order receipts, password resets, notifications), use the API's POST /v1/emails endpoint or the send_email MCP tool. Both send one message synchronously and return its id, applying the same sender, quota, and suppression guards as the dashboard.

All Mail: the message log#

The All Mail section is a searchable log of every individual email you've sent. The Sending tab lists each message with its recipient, status, subject, send time, and originating campaign. Filter by date range and status (delivered, opened, clicked, bounced, complained, failed, sent), and export to CSV.

Click any row to open the message detail: the full event history (sent → delivered → opened → clicked, or bounced/complained with the reason) and a rendered preview of the email that was sent.