Warming client domains at an agency: timelines and ownership

For a clean, newly registered domain with correct DNS, two to three weeks of ramping gets you to a modest daily volume and four to six weeks gets you to a steady production rate. For an inherited client domain with unknown history, you cannot quote a timeline until you have audited it, because a domain that was mailed badly for a year starts below zero and may need remediation before any ramp makes sense.

Audit before you promise a date

Fifteen minutes of checks will change what you commit to.

dig +short TXT example.com              # SPF: one record, under 10 lookups, no +all
dig +short TXT _dmarc.example.com       # policy, and is there a rua= address
dig +short TXT sel._domainkey.example.com
dig +short MX example.com               # who really hosts the mail

Then check the domain against Spamhaus DBL and SURBL, check the sending IP if the client owns one, and ask two questions nobody volunteers: has this domain ever been used for cold outreach, and has anyone else had sending access to it. Note that a SORBS result from any tool is meaningless — SORBS shut down in June 2024. Since 3 September 2026 there is a newer list worth checking, Validity's Heatwave, which lists domains rather than IPs and targets synthetic reputation warming; lookup is at lookup.validity.tools.

Structure the account so one client cannot hurt another

Never share one sending domain across multiple clients. It is tempting operationally and it means one client's complaints degrade everybody's results, with no way to explain it to the others.

A ramp you can hand to an account manager

• Days 1–7: 5–10 sends per mailbox per day, to recipients who will open and reply. Replies first, volume later.
• Days 8–14: 15–25 per mailbox per day. Watch hard bounces; anything over 2% means stop and clean the list.
• Days 15–28: increase by roughly 30% every two or three days while placement holds. Hold, do not increase, on any day a provider's placement drops.
• Day 29 onward: steady state. Consistency beats peak volume — a flat 40 a day per mailbox outperforms 10 one day and 150 the next.

Add mailboxes rather than pushing a single mailbox to its ceiling. Ten mailboxes at 40 a day is a far safer shape than two at 200, and it is more resilient: one bad mailbox is 10% of your capacity instead of half.

Reporting without over-claiming

Agencies get into trouble by reporting numbers that cannot be verified. Google Postmaster Tools retired its domain and IP reputation charts, so "domain reputation: High" is not a line you can put in a deck any more. What you can report honestly is Gmail spam rate from Postmaster Tools, per-provider seed placement, bounce rate, and reply rate. Those are measurable and they are the ones a client's own data will corroborate.

Be equally careful about the warm-up mechanism itself. Volume ramping and genuine engagement are defensible and worth billing for. Fabricated interaction between pools of controlled mailboxes is precisely what Heatwave was built to detect, and because its thresholds are not public, no vendor — including us — can promise a client immunity from it. Promising that is how an agency ends up owning a listing it cannot fix.

What not to do

Do not warm the client's primary domain for cold outreach. One campaign that goes wrong and their invoices stop arriving, and that conversation ends the relationship. Do not start a campaign the day DNS was changed; DMARC aggregate reports take days to tell you whether every stream is aligned. Do not buy aged domains as a shortcut — you are buying an unknown history, and the pattern of a domain changing hands and immediately starting outreach is itself legible to filters. Do not let an account manager raise volume because a deadline moved; the ramp is a technical constraint, not a preference. And do not keep mailing a segment that never engages, in any client's account, for any reason.

When a client domain is already damaged

Stop outbound entirely. Fix the cause — usually list quality or a shared credential. Get authentication fully aligned. Resume only to recipients who have engaged recently, at low volume, for two weeks. If there is a listing, use the list's own free review path once the source is actually off, and not before; a rejected review makes the next one slower. Budget weeks, and tell the client weeks.

MailPilot is built for this shape of work: unlimited mailboxes on every plan, OAuth for Gmail and Outlook or SMTP/IMAP for SES, SendGrid, Mailgun, Postmark and custom relays, SPF/DKIM/DMARC checks per domain, real per-provider placement measurement, and per-mailbox reputation tracked daily so you can show a client which mailbox moved and when.