Frequently Asked Questions

Sending emails

What's the difference between send-email, send-template-email, and send-batch?

Endpoint	Best for	Recipients
`POST /v1/send-email`	Individual emails with direct HTML (transactional)	1
`POST /v1/send-template-email`	Individual emails using a saved template with variables	1
`POST /v1/send-batch`	Bulk sends to multiple recipients	Up to 10,000

Quick rules:

send-email when you generate HTML from your system (confirmations, alerts).
send-template-email when you have templates in the visual editor and only send variables.
send-batch to send the same email (with personalized variables) to many recipients.

Can I send more than 10,000 emails?

Yes. You have two options:

Multiple calls to /v1/send-batch — Split recipients into batches of up to 10,000 and make one call per batch.
Campaigns from the Dashboard — Create a campaign with no limit. The system automatically processes in batches with built-in rate limiting. Ideal for 50k+ emails.

What are the sending limits?

Limit	Value
Recipients per batch request	10,000
Recipients per individual send (`/v1/send-email`)	50
Attachments	10 per email, 10 MB total

Daily and monthly limits also apply depending on your account. When you reach them, sends are queued and resume on their own. Contact support if you need more capacity.

Can I schedule a send for later?

Yes. Use the scheduled_at field with ISO 8601:

{ "scheduled_at": "2026-04-01T10:00:00Z" }

It works in /send-email (accepts ISO 8601, natural language like "tomorrow at 3pm", and the timezone field) and in /v1/send-batch (ISO 8601 only). See Scheduling Sends.

What happens if I send an email to someone who unsubscribed?

The email is skipped automatically. The behavior depends on the endpoint:

/v1/send-template-email: the suppression is detected at request time — it responds 200 with "skipped": true and suppression_reason (see v1 API).
/v1/send-email and /send-email: the suppression is detected at request time — it responds 200 with "suppressed": true and reason: "recipient_suppressed", without queuing anything (see Suppressed recipient).
/v1/send-batch: the API responds 200 and applies the suppression in the background. The email is never sent; the activity ends up with current_status: "suppressed", which can be queried via the Activity API.

In all API send cases, the email.suppressed webhook is also emitted so you can sync your side.The suppression list includes recipients by:

Unsubscribe — click on an unsubscribe link
Hard bounce — permanent bounce
Complaint — marked as spam

How do I track whether an email was delivered?

Each send returns an activity_id (or email_id). Delivery events update the status:

queued → sent → delivered (success)
queued → sent → bounced (bounce)
queued → sent → complained (spam)

Status is visible in Dashboard → Activity, or queryable via the Activity API. For send-batch, there’s one activity_id per recipient.

Domains and deliverability

Why do my emails land in spam?

Most common causes:

Unverified domain — DKIM, SPF, DMARC. Verify with POST /domains/:domain/verify.
Cold domain — needs gradual warming: 150 emails on day 1, 250 on day 2, 400 on day 3, up to around 2,000 by day 7. Ramping all at once burns the domain.
High bounce or complaint rate — clean your list. Above 4% bounces you should pause; above 0.1% complaints reputation drops fast.
Links that don’t match your domain — if the From is yours but links point elsewhere, filters read it as phishing. Fixed with a tracking domain.
Suspicious content — too many links, all caps, words like “FREE”/“OFFER”/“URGENT”, images without alt text.
No unsubscribe link — ReallyQuickEmails adds List-Unsubscribe automatically, but include a visible link.

If everything shows as verified and you still land in spam, the problem is reputation, not configuration. See Deliverability and authentication.And don’t use an email you send to yourself within your own domain as a test: Google penalizes it for resembling spoofing, even when everything is set up correctly.

How do I verify my domain?

Register the domain with POST /domains/register
Configure the 8 DNS records at your provider:
- 1 TXT domain verification
- 3 CNAME DKIM
- 1 TXT SPF
- 1 TXT DMARC
- 1 MX send (Return-Path)
- 1 TXT send (Return-Path)
Wait 5–10 min for propagation
Verify with POST /domains/:domain/verify
When can_send: true, you’re set

Full guide in Domains.

How long does DNS verification take?

Provider	Typical time
Cloudflare	1–5 min
GoDaddy	5–30 min
Namecheap	5–30 min
Route 53 (AWS)	1–5 min
Others	up to 48 h

Templates

What syntax do variables use?

Syntax	Example
Double brace	`{{name}}`
Single brace	`{name}`

Also:

Fallback — {name || "Customer"}
Raw HTML — {!htmlContent}
Loops — {{#each products}}...{{/each}}
Conditionals — {{#if premium}}...{{/if}}

See Templates and Variables.

What formatting helpers are available?

Helper	Use	Example
`formatCurrency`	Currency	`{{formatCurrency total}}` → `$61,970.00`
`multiply`	Multiplication	`{{multiply quantity price}}`
`formatDate`	Human-readable date	`{{formatDate date}}` → `15/3/2026`
`formatDate "long"`	Long format	`{{formatDate date "long"}}` → `domingo, 15 de marzo de 2026`
`default`	Default	`{{default name "Customer"}}`
`json`	Serializes to JSON	`{{json data}}`

Can I use the same template for send-email and send-batch?

Yes. Templates created in the visual editor work in:

POST /v1/send-template-email (individual, template_id + variables)
POST /v1/send-batch (bulk, templateId + data per recipient)
Campaigns from the Dashboard

Campaigns

Difference between send-batch and a campaign?

Aspect	send-batch (API)	Campaign (Dashboard)
Limit	10,000 per request	No limit
Creation	Code (curl, SDK)	Visual 5-step wizard
Template	Direct HTML or templateId	Visual campaign editor
Variables	`data` per recipient	CSV upload, mapping, defaults
Batches	Manual	Automatic
Warming	Manual	Configurable batch mode
Retries	No	Automatic
Stats	Via individual activity_id	Dashboard with aggregate metrics

Rule: send-batch for programmatic integrations. Campaigns for large sends from the UI.

Can I pause a campaign in progress?

Yes. From the Dashboard you can pause a campaign in processing. Emails already queued keep sending, but no new batches are dispatched. Resume from the Dashboard.

What happens if my campaign gets stuck in 'rate_limited'?

Your account’s sending limit was reached. It resumes automatically when the limit resets. You can also resume it manually from the Dashboard.

API and authentication

Where do I find my API keys?

Dashboard → your project → Settings → Integrations → API Keys
Copy the corresponding key:
- Live (sk_live_* or sk_proj_*) → production traffic
- Test (sk_test_*) → development, doesn’t consume quota

See API Keys for details.

Why am I getting a 401 error?

Cause	Solution
Missing `Authorization` header	Add `Authorization: Bearer sk_live_...`
Incorrect format	Check the space after `Bearer`
Unrecognized prefix	Only `sk_proj_`, `sk_live_`, `sk_test_*`
Invalid or revoked key	Generate a new one from Settings → API Keys

Does the API have rate limiting?

The endpoints don’t have their own rate limiting; the limit is imposed by your account’s sending capacity. When you reach it, emails are queued and sent on their own once capacity is available.

How do I avoid double sends on retries?

Pass an Idempotency-Key: <unique-string> header (1–256 characters) in /send-email or /v1/send-batch. A retry with the same key within 24h returns the cached response with Idempotency-Replayed: true. See API Keys.

Support

Contact us at harold@dropout.cl, including: Project ID, endpoint used, request body, error/response, and approximate timestamp.

Guides

The app

Concepts

API Reference

Sending emails

Domains and deliverability

Templates

Campaigns

API and authentication

Support

​Sending emails

​Domains and deliverability

​Templates

​Campaigns

​API and authentication

​Support

Sending emails

Domains and deliverability

Templates

Campaigns

API and authentication

Support