Email Warmup Service — Built Into Every Send on Mails.ai

How email warmup services work

A traditional email warmup service signs your mailbox into a network of seed inboxes. Those inboxes send each other mail, open it, reply to it and drag it out of spam — manufacturing the engagement signals that mailbox providers look for. The goal is to make a cold domain or IP look more established than it has earned.

The approach has limits. Providers like Gmail and Outlook have been discounting seed-network traffic for years — the signals are real interactions, but not from real recipients. And the moment you stop paying for the email warmup service, the artificial engagement stops with it.

Why you do not need a separate email warmup service here

You do not need a warmup tool to send on Mails.ai, because there is nothing cold to start from. Your agent sends from agent.yourworkspace@send.mails.ai on a shared rail with a real record of transactional sending, low complaint rates and verified authentication. It inherits that record on its first message. No subscription, no seed list, no ramp.

What keeps that rail warm is the traffic on it, not a tool: every send is checked before it leaves, and an agent whose complaint rate passes 0.3% is suspended automatically. The mail that moves through the shared infrastructure is real transactional and agent mail — and that is what makes the inherited sender reputation worth inheriting.

Mails.ai vs standalone email warmup services

Email warmup for your own custom domain

If you send from your own domain, that domain has no standing of its own — and no email warmup service can create one for you. Mailbox providers weight opens, replies, complaints and spam-folder rescues from real recipients. Mail circulated between seed inboxes produces a pattern, not a reputation, and providers have been discounting that pattern for years.

We will not claim to warm your domain. What you get instead is the part that is real:

• A DKIM keypair generated for your domain automatically — one DNS record to publish
• Delivery over mail servers we rent and keep warm, not a box rented this morning
• SPF guidance that merges with your existing record rather than replacing it
• No nameserver move, and no seed network anywhere in the path

Your domain’s standing then builds from the mail your product actually sends. One limit to know up front: mail from a custom domain cannot reach Outlook or Hotmail recipients yet — mail from the shared send.mails.ai domain reaches them normally. See custom domain email for AI agents for the full setup walkthrough.

Send from day one — no warmup wait

There is no warmup period to sit through on the shared rail, and for your own domain the thing to watch is delivery on real traffic rather than a ramp schedule:

# Send — no warmup state to wait on
curl https://api.mails.ai/v1/messages \
  -H "Authorization: Bearer $MAILS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "agent": "hello",
    "to": ["customer@example.com"],
    "subject": "Your order shipped",
    "body_text": "Tracking: 1Z999..."
  }'

# Your own domain's verification state (this is what gates custom-domain sending)
curl https://api.mails.ai/v1/domains/dom_123 \
  -H "Authorization: Bearer $MAILS_API_KEY"

# {
#   "id": "dom_123",
#   "domain": "mail.yourapp.com",
#   "status": "verified",         // pending -> verifying -> verified
#   "provider": "ownmetal",
#   "dns_records": [ /* each with "verified": true */ ],
#   "fail_reason": null
# }

Shared address or your own domain

Agents that need an inbox immediately start on their own AI email address and need no warmup at all. Move to a custom domain when you want your brand in the from address — add it, publish the DKIM record, and sends switch over once it verifies. Nothing about the shared rail stops working while you do.

What it costs — no email warmup service fee

There is no warmup line item, because there is no warmup product to sell separately. The free tier is $0/mo and covers 3,000 emails and 3,000 inbound replies a month, and one agent on the shared sending domain — warm rail included, because that is simply how the product sends. Sending from your own domain starts at $20/mo, which also lifts you to five agents.

A dedicated IP is available on request on Scale — see automated dedicated IP warm-up for why most senders are better off without one, free email warmup for the short version, or email service that handles dedicated IPs and warmup options if you are evaluating which platform covers both. For pricing details, the free tier is enough to test everything the email warmup service provides.