Email Warmup for Cold Email Agencies
Agencies don't run one mailbox. They run ten, fifty, or a hundred — across client domains, managed at scale. The economics of warmup look completely different when you're responsible for all of them.
Most warmup tools were designed for a single founder with one sending domain. They work at that scale. They get expensive, complicated, and unpredictable the moment you're managing deliverability across multiple clients.
The warmup problem at agency scale
Most warmup tools charge per mailbox. That made sense when a solo sender was warming one domain. For an agency managing multiple clients, the maths breaks quickly.
Ten mailboxes at $20 per mailbox is $200/month before you've written a single sequence. At 50 mailboxes, you're spending more on warmup than most agencies spend on their entire stack. And all of that spend is going to the same underlying process: generating peer traffic to tell Gmail and Outlook that a mailbox belongs to a real person.
Warmerly charges a flat monthly rate. Connect ten mailboxes or a hundred — the price stays the same. For agencies managing multiple clients, that predictability matters as much as the warmup quality itself.
What agencies actually need from a warmup tool
Most warmup tools are designed for solo senders. They work, but the workflow doesn't scale:
- One billing account, one login, mailboxes connected one at a time.
- Reports per mailbox in isolation, no cross-client view.
- No alerting when something breaks — you find out when the client notices.
- No daily authentication checks, so DNS changes silently kill deliverability.
An agency needs something different. You need to see all your client mailboxes in one view, get alerted when something breaks, and know that warmup quality is consistent across all of them — not just the ones you happened to check today.
What good warmup looks like for outbound agencies
The fundamentals are the same regardless of scale: real peer traffic, spam-folder rescue, quoted replies, and positive engagement signals. The difference at agency scale is consistency and continuity.
When a client domain goes quiet for two weeks between campaign batches, reputation decays. When a new client sends from a fresh domain before warmup is complete, deliverability collapses. When an authentication record breaks and nobody notices for a week, the entire client pipeline stops working. Good agency warmup accounts for all three.
- Warmup runs continuously — not just before campaigns but as ongoing maintenance.
- New client domains get a proper ramp before any cold sending starts.
- Authentication is monitored daily so DNS changes don't silently break deliverability.
- Health drops trigger alerts before they become client complaints.
- Inbox placement is tested across multiple providers so you catch Outlook problems alongside Gmail ones.
How Warmerly fits into an agency workflow
Warmerly is warmup-only. It connects to your clients' Gmail and Outlook mailboxes via OAuth, runs the warmup engine in the background, and surfaces health data in a single dashboard. It does not touch your campaign tool, your sequences, or your client's primary business mail — it just handles the reputation layer underneath.
That separation matters for agencies. You can use Warmerly alongside Apollo, Instantly, Smartlead, lemlist, or any other sending tool your clients use. The warmup mailbox is the same mailbox your campaign tool sends from — Warmerly just makes sure it's in good standing before and during each campaign.
Warmerly at £9/month flat covers every mailbox you manage. If you currently pay per-mailbox pricing elsewhere, calculate what you spend for 20 or 50 mailboxes. The difference usually pays for several months of Warmerly.
Common mistakes agencies make with warmup
These come up in almost every agency audit.
- Starting cold sends before warmup is complete. Two weeks minimum for a new domain, three if it's under 30 days old. Rushing this under client pressure is the single most common cause of deliverability failures.
- Stopping warmup between campaigns. Warmup isn't a launch activity — it's maintenance. A mailbox that sits idle for three weeks loses reputation. Keep warmup running at reduced volume during quiet periods.
- Sharing a sending domain with primary business mail. Keep outreach domains separate from anything clients or partners receive business-critical mail on. A burnt sending domain is recoverable. A burnt primary domain is not.
- Ignoring authentication failures. SPF and DKIM misconfigurations are often silent — the mailbox still sends, it just spam-folders at a higher rate. Daily auth monitoring catches this before it compounds across client campaigns.
- Only checking Gmail placement. A campaign that inboxes on Gmail but spam-folders on Outlook looks like a 4% reply rate when it's really two different outcomes. Seed testing across both providers is the only way to see the full picture.
- Warming mailboxes on the same domain all at once. Gmail watches domain-level sending totals, not just per-mailbox counts. Ramp each mailbox gradually and stagger new additions so the domain total doesn't spike.
What Warmerly gives your agency
Every feature below is available on every plan, including the starting tier.
Unlimited mailboxes, one flat rate
Add every client mailbox you manage. Warmerly's flat monthly price doesn't change as you grow. No per-seat negotiations, no surprise bills at end of month.
Daily authentication monitoring
Warmerly checks SPF, DKIM, DMARC, and MTA-STS every day for every connected mailbox. If a record breaks or goes missing, you get a remediation note before it affects deliverability.
10-minute spam-folder rescue
When peer warmup messages land in spam, Warmerly moves them out within 10 minutes. The fast rescue window matters because Gmail's reputation snapshot is influenced by folder state at the time of the daily update.
5-provider inbox placement
Placement seeds run across Gmail, Outlook.com, Microsoft 365, Yahoo, and a fifth provider. Agencies targeting enterprise buyers need Outlook placement data, not just Gmail numbers.
Health timeline per mailbox
Every reputation event is logged with a timestamp and context. When a client asks why their reply rate dropped last Tuesday, you have the data to answer them.
Works alongside your campaign stack
Warmerly is warmup-only. It runs in parallel with Instantly, Smartlead, Apollo, lemlist, or any tool you already use. No migration, no routing changes.
Check your email health before scaling outreach.
Connect a mailbox in 60 seconds. Warmerly starts monitoring immediately and begins the warmup sequence automatically.
Questions
How many mailboxes can I connect to Warmerly?
Every Warmerly plan includes unlimited mailboxes. You can connect as many client mailboxes as you manage, and the monthly cost stays the same. There are no per-seat charges or volume tiers.
Does Warmerly support both Gmail and Outlook?
Yes. Warmerly connects via Google OAuth for Gmail and Google Workspace mailboxes, and Microsoft OAuth for Outlook.com and Microsoft 365. Both are fully supported on every plan.
Can Warmerly run alongside the campaign tools my clients already use?
Yes. Warmerly only warms the mailbox. Your campaign tool — whether that's Apollo, Instantly, Smartlead, lemlist, or anything else — runs from the same Gmail or Microsoft account. There's no routing conflict and no DNS change required.
What happens if I need to add or remove mailboxes mid-month?
Add and remove mailboxes freely. The flat monthly rate covers your account regardless of how many mailboxes are active at any given time. You won't be billed differently for adding a client mid-month.
How do I move a client's mailbox from another warmup tool to Warmerly?
Disconnect the mailbox from your current warmup tool, then connect it to Warmerly via the same Google or Microsoft OAuth flow. Choose a ramp schedule that matches the current send volume. Mailbox reputation lives at Gmail and Microsoft, not at the warmup tool, so nothing is lost in the switch. Each mailbox takes about 2 minutes.
Will Warmerly alert me if a client's authentication breaks?
Yes. Warmerly monitors SPF, DKIM, DMARC, and MTA-STS daily for every connected mailbox. If a record is missing, misconfigured, or changes unexpectedly, you'll receive an alert with remediation steps — before it causes a deliverability problem.
Warm all your client mailboxes for one flat fee.
Connect a mailbox in 60 seconds. 14-day free trial, no card required. Cancel any time.