How to Audit an Outbound Agency Before You Sign

The best question I have ever heard a founder ask an outbound agency was not about results. It was: "Show me the Postmaster Tools screen for your worst-performing client this month."

The agency said no. He signed with someone else, and the someone else showed him a spam complaint rate of 0.04% and a bounce rate under 2% on a live account. Eight months later that programme is still running.

Here is the short version. Auditing an outbound agency is not about case studies. It is about six things you can verify before money changes hands: whose domains they send from, what their deliverability numbers look like on a live account today, who does the actual work, where the data comes from, how a meeting is defined, and how you get out.

1. Whose domains are they sending from

This is the first question and it eliminates a surprising number of vendors.

An agency should buy and warm secondary domains for you, not send from your primary. If your main domain gets a reputation problem, your invoices and support replies start landing in spam, and that damage takes months to undo.

Ask which domains they will register, how long the warm-up takes, and who owns the domains at the end of the contract. Four to six weeks of warming before meaningful volume is normal. Anyone promising meetings in week one is either sending from your primary or reusing domains that are already tired.

2. Their deliverability numbers, on a live account

Google publishes hard thresholds and they are not negotiable. Gmail asks bulk senders to keep the spam rate reported in Postmaster Tools below 0.10% and warns that reaching 0.30% or higher increases spam classification. Senders above 5,000 messages a day need SPF and DKIM together, a DMARC record, and one-click unsubscribe on marketing mail. Those requirements have applied since February 2024, set out in Google's own sender guidelines.

So ask to see a screen share of Postmaster Tools on an account they run right now. Not a PDF. Not last quarter. A live account.

What you want to see is spam complaint rate comfortably under 0.10%, bounce rate under about 3%, and authentication passing. What you do not want to hear is that they cannot show you client data, which is a fair objection for names and a poor one for a redacted deliverability screen.

3. Who actually does the work

Ask who writes the sequences, who builds the lists, and who reads the replies. Then ask to meet them.

The pattern to watch for is a senior person on the sales call and an offshore pod you never speak to afterwards. That is not automatically bad. Plenty of good programmes run that way. It is bad when it is not disclosed, because it changes what you can expect from turnaround times and from the quality of reply handling.

Reply handling is the part that gets outsourced most quietly and matters most. A reply is a human moment. If it is being triaged by someone three steps removed from your product, you will lose deals in the inbox without ever knowing it happened.

4. Where the data comes from

"We have a proprietary database" usually means a licence to somebody else's. Ask which providers, ask what the verification process is, and ask what the acceptable bounce rate is before a list gets sent.

Better agencies build lists from signals rather than filters. There is a real difference between a list of companies that match a firmographic profile and a list of companies that did something last week suggesting they have the problem you solve. We wrote up that distinction in the signal-based outbound guide.

5. How a meeting is defined

Get the qualification clause in writing before you discuss rates. Title band, company size range, a budget or timeline condition, and whether the meeting counts when booked or when held.

Then get the replacement policy. No-shows and clearly unqualified meetings should be replaced rather than credited, with a time limit on the replacement.

This is the term that decides whether the engagement works, and it is where most of the money is quietly lost. Retainer versus pay-per-meeting goes into how the pricing model changes the incentive behind that clause.

6. How you get out

A three-month initial term with a break clause. Domains and lists transfer to you at the end. Sequences and reply data are yours.

An agency confident in its own work gives you this without a fight. One that will not is telling you it expects the results to need a longer runway than it is willing to promise out loud.

Here is what most people get wrong

They ask for case studies.

Case studies are the one artefact an agency fully controls. They are selected, retold, and usually undated. I have never learned anything from one that I could not have learned faster from a reference call with a client who churned.

So ask for that instead. "Give me two clients who left in the last year." A good agency will have some, will say why they left, and will let you speak to one. That conversation tells you more than a deck ever will.

And ask for the reporting template up front. If the monthly report leads with meetings and does not include sends, bounce rate, spam complaint rate and reply rate, you will not be able to tell a good month from a domain quietly burning down. The metrics side of this is covered in cost per booked meeting.

The audit in one page

• Secondary domains, registered for you, warmed four to six weeks, transferable at exit
• Live Postmaster Tools view: spam rate under 0.10%, bounce under 3%, SPF, DKIM and DMARC passing
• Named people doing list building, copy and reply triage, and a call with them
• Data providers named, verification process explained, bounce threshold agreed
• Qualification clause you wrote, billing on held meetings, written replacement policy
• Three-month term, break clause, domains and data transfer at exit
• Two churned client references, and a reporting template that shows deliverability next to meetings

FAQ

What should I ask an outbound agency before signing?

Ask whose domains they send from, to see live Postmaster Tools data, who does the day-to-day work, where the data comes from, how a meeting is defined, and what happens to your domains and lists when you leave.

What is a good spam complaint rate?

Google asks bulk senders to stay below 0.10% in Postmaster Tools and flags 0.30% or higher as the point where spam classification increases. Anything sustained above 0.10% needs an explanation.

Should an agency send from my main domain?

No. Secondary domains protect your primary. If an agency proposes sending from your main domain, treat it as a reason to walk.

How long should an outbound agency contract be?

Three months to start, with a break clause. Twelve-month lock-ins ask you to bet on a system you have not seen run yet.

Are agency case studies worth reading?

Not for diligence. Ask for references from clients who left instead, and for a live look at the numbers rather than a retold version of them.

What if the agency will not show live data?

Redacted deliverability screens contain no client names and no contact data, so there is no confidentiality reason to withhold them. Refusal is information.

Should I hire an agency or build the capability in-house?

It depends on whether you are buying a person, a service or a system. We laid out the three options and what each costs in fractional VP Sales vs AI SDR vs agency.

Where to start

Send the seven-line audit above to whichever agency is currently in your inbox and see how much of it comes back without a follow-up call. The gaps are your answer.

If you would rather have someone run the diligence with you, book a GTM audit.