TL;DR
- The US candidate inbox landscape is more Gmail-heavy than the UK. If you’ve only ever warmed up with Microsoft in mind, your US reputation is still at zero.
- Sending cold outreach from your primary UK domain into American inboxes is a risk to your whole business (not just the US campaign).
- Google Postmaster Tools is free, takes 10 minutes to set up, and is the only direct window into how Gmail sees your domain. You need it running before you start.
- The practical checklist before your first US send: dedicated sending domain, SPF, DKIM, DMARC alignment, Postmaster Tools active, warm-up at least six to eight weeks in.
If you’ve read our post on domain strategy for US market entry, you know the case for registering your .com early and giving it time to age. That’s the groundwork.
This article is what comes next. You have the domain. Now the question is what to actually do with it and what happens to your deliverability, in both markets, if you get this part wrong.
The US inbox landscape is not what you’re used to
When you’re doing outreach in the UK, your audience is predominantly Microsoft 365. Hiring managers, in-house talent teams, commercial prospects, most of them are on Outlook. Learning to stay on the right side of Microsoft’s filtering logic is, for most UK recruitment agencies, the main game.
In the US, that split looks different. Gmail is significantly more dominant, particularly in the sectors UK agencies typically target on their first push into the market: tech, professional services, start-ups, and the mid-market. Corporate Google Workspace deployments are far more common in the US than the UK. You’ll also encounter more Proofpoint and Mimecast sitting as security gateways in front of enterprise Microsoft accounts. Adding a filtering layer that doesn’t evaluate your domain the same way Gmail does.
This matters because the things you’ve learned about maintaining deliverability with Microsoft in mind don’t fully transfer. Gmail has its own reputation model, its own spam complaint thresholds, and its own tooling. If you’ve never sent to Gmail users at volume before, you don’t have a reputation with Google. You have zero. Which is almost as bad as a negative.
Sending reputation doesn’t cross borders
Your UK domain might be in excellent health. Good authentication, clean sending history, years of legitimate outreach that Microsoft and Google in the UK trust. You have a reputation. It’s just built on the sending behaviour that inbox providers have observed so far.
When you start cold outreach into US inboxes at volume, that existing goodwill doesn’t transfer the way you might expect. A new wave of cold emails to Gmail accounts the domain has never touched before can look, to Google’s systems, like a domain that has suddenly changed behaviour. That’s a flag.
If that outreach generates spam complaints (and even a well-targeted cold sequence will generate some, particularly from recipients who don’t recognise a UK agency name) those signals feed back into how Gmail treats your domain globally. Not just your Austin prospects. Your UK candidate job alerts, your client emails, your team’s day-to-day correspondence, all of it flows through the same domain reputation.
That’s the real risk. One poorly managed US cold outreach push, on your primary domain, can affect deliverability for your entire business. It doesn’t always happen. But it’s the kind of thing that’s very easy to avoid in advance and genuinely painful to recover from after the fact.
Set up Google Postmaster Tools before you send anything
Google Postmaster Tools is free. It requires domain ownership verification (a TXT record in your DNS) and takes about 10 minutes to configure. Once it’s in place and you’re sending enough volume to register data (typically around 100 or more emails to Gmail addresses per day), it gives you the only direct window into how Gmail sees your domain that isn’t behind a paywall.
What you’ll see:
Domain reputation — rated High, Medium, Low, or Bad. High is where you need to stay. Dropping from High to Medium is recoverable. Low or Bad typically requires a longer period of disciplined, low-volume sending to climb back from, and during that time your outreach is largely going to spam.
Spam rate — the percentage of your email that Gmail users are marking as spam. Google’s own bulk sender guidance asks for below 0.1% as a steady state, and never above 0.3%. In a cold outreach context, on lists of any real scale, that ceiling is closer than it looks.
Authentication — whether your messages are passing SPF, DKIM, and DMARC checks as Gmail sees them. This is the baseline. If authentication isn’t aligned, reputation is almost irrelevant.
Delivery errors — failed deliveries, usually caused by IP or domain-level blocks.
The value of Postmaster Tools is the early warning. By the time your consultants notice that open rates have dropped, you’re already a week or two into a problem that could have been caught on day one. Get it running on your sending domain before the first email goes out and make sure your DMARC reporting covers the new domain too, so you have authentication visibility across all providers, not just Gmail.
Why your primary domain is the wrong tool for US cold outreach
The answer to the cross-contamination risk above is straightforward: don’t use your primary domain for cold outreach into a new market.
Your primary domain carries the sending history that keeps your whole business’s email working. Candidate comms, client updates, ATS notifications, interview confirmations. Cold outreach is inherently higher risk. Lists in a new market are never perfectly clean. Complaint rates are harder to control when recipients don’t recognise your agency name. Running that risk through your main domain, at the same time as everything else, means any fallout affects everything attached to it.
A dedicated sending domain for US cold outreach separates those risks. Practically, for a UK agency entering the US market, that means a .com variant of your brand properly authenticated, configured independently, and introduced to inbox providers through a structured warm-up before anyone on the team starts sending sequences from it.
The authentication and warm-up checklist
Before your dedicated US sending domain touches a single cold prospect, these need to be in place:
SPF — a DNS record that tells receiving servers which mail infrastructure is authorised to send on behalf of your domain. If you’re using an outreach tool, that platform’s sending infrastructure needs to be listed.
DKIM — a cryptographic signature that lets receiving servers verify your emails haven’t been tampered with in transit. For most modern sending platforms, this is configured by adding CNAME or TXT records to your DNS using values your platform supplies.
DMARC — the policy that ties SPF and DKIM together and tells inbox providers what to do with mail that fails authentication checks. Start at p=none (monitoring only) while you establish a baseline on the new domain, then move to p=quarantine once you’re confident authentication is passing cleanly. DMARC also enables reporting (through Quinset Powermail or similar) so you can see authentication failures by sending source from day one.
Alignment — SPF and DKIM each need to align with the domain your recipients actually see in the “From” address. Misalignment is one of the most common mistakes when an agency sets up a new sending domain quickly. You can check your current domain authentication status at quinset.co.uk/domains/.
Warm-up — a new domain needs a structured ramp before it handles cold outreach at volume. Start with warm-up infrastructure (tools like Warmy.io or Mailreach simulate low-volume, engagement-positive sending between seed inboxes), then introduce real contacts with a genuine reason to engage positively before any cold sequences begin. Realistically, this takes six to eight weeks minimum for a domain intended to handle meaningful outreach volume. The detailed warm-up guide is here if you want to understand how the process actually works under the hood.
Postmaster Tools active — as above. Not optional if you’re sending into Gmail-heavy US inboxes.
What this means for UK recruiters going into the US
Done in the right order, none of this is complicated. Register your .com early (covered in the previous post). Authenticate it properly. Warm it up over six to eight weeks. Get Postmaster Tools running. Keep your primary UK domain well away from cold US outreach.
What creates problems is compressing the timeline. Registering the domain in month one and starting cold sequences in month two because the desk is open and the pressure is on to generate pipeline. That’s when reputation damage happens, and it rarely stays contained to the new market.
If you’re working towards a US launch and want someone to walk through the infrastructure setup with you before you start sending, book a free consultation at quinset.co.uk/bookings/. It’s a short conversation that tends to save a much longer one later.
FAQ
Do I need separate DMARC reporting for my US sending domain?
Yes. DMARC reporting is configured per domain, so your new sending domain needs its own DMARC record and its own reporting destination. If you’re using Quinset Powermail, both your UK primary domain and US sending domain can be monitored from the same dashboard.
What counts as “enough volume” for Google Postmaster Tools to show data?
Google typically requires around 100 or more emails to Gmail addresses per day before reputation data populates. During early warm-up stages you may not see data immediately. That’s normal. It will appear as volume builds.
Can I just monitor Postmaster Tools after I start sending, rather than before?
Technically yes, but you lose the baseline. Setting it up before you send means you can see how the domain registers from its first interactions with Gmail, rather than arriving mid-problem. Set it up at the same time as authentication.
How do I know if my authentication is aligned, not just passing?
Passing and aligned aren’t the same thing. SPF can pass on the sending server’s domain while failing alignment with your From address. Use a tool like MXToolbox or mail-tester.com to send a test message and check both pass and alignment status before running any sequences. Quinset’s free domain health check will also surface alignment issues.
What’s the risk if I skip the warm-up and just start sending?
The domain enters inboxes with no positive reputation and potentially on age-based blocklists if it’s under 30 days old. Early spam complaints have an outsized effect on a domain with no track record. Recovery is possible but slow. Typically two to four weeks of disciplined low-volume sending before reputation starts to recover, during which cold outreach is largely wasted.
Need help?
Leverage years of experience working with recruiters targeting US domination and book a call with Ben Fielding, the only email deliverability expert dedicated to the recruitment sector.
