Domain warm-up (Smailor)

This guide complements the operational controls in Dashboard → Settings → Developer → Warm-up (Pro / Business).

Why warm up

Mailbox providers throttle and score new or low-history sending domains. A sudden spike of identical outbound mail looks abusive. Responsible warm-up ramps volume while keeping SPF/DKIM/DMARC aligned and reacting to bounces.

Included from Pro onward

Automated guarded sends—daily caps, minimum spacing between queued envelopes, inbound loop suppression ([Smailor Warm-up] subject marker)—are available once you subscribe to Pro or Business. Free / Starter tiers can still follow the DNS playbook below manually.

DNS hygiene before volume

DMARC: start with aggregate monitoring (p=none), tighten to quarantine with low pct when reports stay clean, then consider reject only when SPF and DKIM are fully aligned everywhere you send.
SPF: list every authorised source (inbound MX includes—e.g. Cloudflare—as well as your ESP’s include string copied from their dashboard). Move from softfail (~all) to hardfail (-all) only when the list is complete.
DKIM: publish the signing records Smailor gives you for each domain you send from (see Deliverability and the DKIM guide).

Step-by-step records: see Documentation → Email setup.

Operational guardrails (product)

Guardrail	Purpose
Daily cap per domain	Stops unchecked bursts; at most 20 messages per domain per day in the product
Minimum minutes between automated sends	Spreads signalling over time (“human-like” pacing)
Recipient is an inbox on your warmed domain	Hits that domain’s MX path (login-only abuse prevention handled in product)
Subject marker + inbound discard	Returning mail does not spawn tickets

Warm-up mail counts toward your monthly send quota.

Automated scheduling

On smailor.com, the platform runs warm-up dispatches for you. Configure caps and pacing in the dashboard; you do not need jobs, tokens, or private endpoints on your side.

Manual Send now in the dashboard still respects caps but skips the spacing wait once.

Avoid

Thousands of ping-pong messages between sibling domains without real mailbox diversity.
Identical subjects/bodies fired on rigid schedules.
Ignoring bounce or complaint spikes.
Breaking third-party ESP terms (e.g. opening many free accounts purely to circumvent limits).

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