Operations

IP / domain warm-up

A brand-new sending domain has zero reputation. Sending 10,000 emails on day one is the single fastest way to land in spam permanently. Warm-up is the slow-burn ramp that proves to Gmail, Outlook, and Yahoo that you're a real sender — not a freshly-spun bulk-mail operation.

The 11-tier curve

SendBolt's warmup gate (the system that throttles your outbound send rate) walks each verified sending domain up a fixed curve. New domains start at tier 0 and graduate one tier per day so long as the previous day's delivery rate stayed healthy:

At tier 10 you're considered fully warm. Most operators reach tier 10 in 14-21 days assuming clean traffic.

How the gate enforces it

Every outbound send hits the warmup gate first. The gate looks up the (tenant, domain) pair and checks the day's rolling counter against the tier cap. Three outcomes:

• allow — counter incremented, send proceeds
• deny + deferred — over cap; send queued for tomorrow at 00:00 UTC
• deny + dropped — over cap AND the recipient is on the suppression list (suppression always wins)

The auto-ramp worker

Tier promotions happen automatically once per day at 02:00 UTC. The auto-ramp worker walks every verified domain and:

1. Looks at yesterday's delivery + bounce + complaint rates
2. Healthy (bounce < 3%, complaint < 0.1%, delivery rate > 95%): promotes the domain to the next tier
3. Mixed (any of the three is borderline): holds at the current tier
4. Bad (bounce > 5% or complaint > 0.3%): demotes by one tier OR auto-pauses the domain at 3% bounces

Operator override: a super-admin can manually advance / hold / demote a tier from /dashboard/warmupvia the "Override tier" action. Use it sparingly — auto-ramp's decisions are usually right.

30-day warmup schedule

SendBolt supports a per-tenant pre-planned schedule. Instead of "send whatever you have, throttled to the tier cap", you can declare ahead-of-time: "day 0 = 20 sends to warmest-engagement signup confirms, day 1 = 30 sends to welcome, … day 29 = 10,000 daily digest". The dispatcher picks rows off that schedule each morning.

Generate via POST /api/v1/admin/tenants/{id}/warmup-schedule/generate:

curl -X POST "$API/api/v1/admin/tenants/$TID/warmup-schedule/generate" \
  -H "Authorization: Bearer $SUPER_ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "start_date": "2026-05-13",
    "total_target_recipients": 10000,
    "ramp_strategy": "standard"
  }'

Ramp strategies: standard (default; the 11-tier curve above), conservative (half the cap each day; useful for re-warming a previously-burnt domain), aggressive (1.5× cap; only if you have strong engagement signals already).

Per-ESP caps

Within a tier cap, SendBolt can further reconcile per-(tenant, ESP) sub-caps so you don't blast 100% of the tier-7 10k/day to Gmail and tank your Gmail-specific reputation. Per-ESP enforcement is gated behind WARMUP_PER_ESP_ENFORCE=true (default off today; advisory-only). See GET /admin/tenants/{id}/warmup/reconciliation for the report.

What you should NOT do

• Override your way to tier 10 on day 1 to "save time" — you'll burn the domain in 48 hours
• Send to a 50k-row purchased list on a brand-new domain. Period.
• Mix transactional + marketing on the same domain unless you have separate sub-domains (`tx.acme.com` + `news.acme.com`). Receivers reputation per-(domain, sub-domain).
• Pause warmup and resume 30 days later expecting the previous tier to stick. The tier resets after 14 days of no sends.

Monitoring

• /dashboard/warmup — current tier per domain + ramp ETA
• /dashboard/warmup/schedule — your 30-day plan
• /dashboard/admin/observability — platform-wide warmup occupancy
• Slack #sendbolt — auto-pings on bounce-pause and tier demote

FAQ

How long does a full warmup take?

14-21 days with clean traffic. Faster if you already have engagement (existing subscribers re-engaging on a new domain). Slower if your list has any bounces > 3%.

I want to send a 100k blast tomorrow. Can warmup just be "off"?

No — but you can buy a pre-warmed dedicated IP / IP pool which arrives at tier 7-8 from day one. Talk to rahul@sendbolt.io if you need this.

Do transactional sends count toward the tier cap?

Yes. From the receiver's perspective there's no difference between transactional and marketing — your domain's reputation is one number. The gate counts every outbound send.