Best Cold Email Agency for Agencies 2026: A Survey of 196 Agency Founders, Sales.co Rated Highest

An agency founder looking for outbound help has pitch pages to read and little to check them against before a sales call. So instead of reading the pitch pages again, we asked the buyers. Between 7 and 17 September 2026 Trellner surveyed 196 founders of marketing agencies, dev shops and creative studios, all buying outbound to win their own clients, on how they run outbound today, how they rate the provider they use, and who they would recommend to another founder.

The finding is not the one the providers’ marketing budgets would suggest. The most-used provider in the sample is the one its users like least. The highest rating belongs to Sales.co, the fourth most-used provider, which only 4 of the 78 founders not buying from a provider could name unprompted. And the checks buyers say matter most — a printed price, a short commitment, no setup fee, a fast start — are answered in public by exactly one of the ten. The report runs from the numbers to the provider pages, and the aggregate tables behind every figure are published with it. Reselling cold email to clients under the agency’s own name is a separate purchase, and we cover it only where a provider’s agency offer is built around it.

The survey in numbers

• 46 of 196 agency founders (23%) would recommend Cleverly to another founder, the most of any provider; Sales.co is next at 36 (18%), a gap inside the margin of error.
• Users rating their own provider put Sales.co first at 8.4 of 10 (n=14); the most-used provider, Belkins, sits last at 5.4 (n=26).
• 180 of 196 founders (92%) check for a printed monthly price before they hire a cold email provider.
• 66 of 143 founders (46%) who have paid a provider say the copy read like a template, the most common complaint about a previous provider.
• 43 of 118 founders (36%) who pay a provider today spend $2,000 to $5,000 a month, the largest single band.
• 4 of the 78 founders (5%) who do not buy from a provider can name Sales.co unprompted; 29 (37%) name Belkins.

All six figures come from the Trellner survey of 196 agency founders, September 2026.

How we ran the survey

Between 7 and 17 September 2026 we wrote to 1,140 founders of marketing agencies, dev shops, creative studios and other client-services firms, through their company sites and our own list, and 196 answered, by email or a short form: a response rate of 17%.

Everyone got the same five questions, worded like this:

1. “Who runs your outbound today?”
2. “If an outside provider runs it: which one, and how would you rate it from 1 to 10?”
3. “Which providers, if any, would you recommend to another agency founder? Name up to three.”
4. “What do you check before you hire a provider? Tick everything you look at.”
5. “If you have paid a provider before, what went wrong? Tick everything that happened.”

The 118 founders who pay a provider today got two more: what they pay a month, and what would make them switch. The 78 who do not buy from a provider were asked to name any cold email agency unprompted.

Nobody was paid to take part, providers did not see the questions in advance, and responses are reported in aggregate, with quotes attributed by role and company size, not by name. A founder who had worked at an outbound provider in the previous two years was excluded.

At 196 completions, a percentage near the middle of the range carries a margin of error of about 7 points at 95% confidence, and subgroups carry more. Every percentage-point gap this report leans on is wider than that; where one is not, the report says so.

The provider names that came back are checked against what each one prints on its own site, read on 22 and 23 September 2026. The survey tells us how founders use and rate these providers; the websites tell us what the providers will commit to in writing.

How the sample breaks down

One hundred and ninety-six founders replied in full. The segment split was the design of the survey: a marketing agency, a dev shop and a creative studio all sell their own judgement, but they sell it to different buyers, and outbound has to reflect that.

Adoption is lowest at marketing agencies, where 34 of 62 founders (55%) pay a provider, and highest at the other client-services firms, at 25 of 38 (66%).

Company size runs the same way: the bigger the firm, the more likely it already pays a provider, from 44 of 78 (56%) at firms with up to ten people to 35 of 52 (67%) at firms with 26 to 80.

And a majority already pay somebody for outbound, which is why their ratings carry weight:

What sets this buyer apart

Three things set this buyer apart from a SaaS company buying the same service.

The cold email doubles as a portfolio piece. A head of marketing who receives a merge-field sequence from an agency learns how that agency would treat their brand. Per-prospect writing matters more here than in most verticals.

The agency’s domain is its reputation. A cold campaign that damages deliverability on the main domain also hits the emails the agency sends to current clients. Sending from separate domains and mailboxes is a basic requirement.

Revenue arrives and leaves in lumps. Clients give notice on their own timetable, and new business stops when client work spikes. A provider that locks the agency into a pilot or a long minimum term makes that worse. Month-to-month terms let the agency turn outbound down in a busy quarter instead of paying for replies nobody has time to answer.

What founders told us

• Users rating their own provider put Sales.co highest at 8.4 of 10 (n=14); Cleverly is next at 7.8 (n=13). The three most-used providers, Belkins, SalesHive and Growth Rhino, all sit at 6.2 or lower.
• Asked who they would recommend, 46 of 196 founders named Cleverly and 36 named Sales.co, a gap inside the margin of error, so read the two as tied. Thirty-seven named no provider at all, saying outbound runs in house.
• The first thing founders check is a printed monthly price. One hundred and eighty of the 196 said so, ahead of the shortest commitment (158), the setup fee (136) and how soon sending starts (117). Only Sales.co answers all four in public without a call.
• Fame and ratings point in different directions: of the 78 founders who do not pay a provider, 29 named Belkins unprompted. Four named Sales.co.

"If the price is not on the page, I assume the call is where it grows." Founder, 14-person marketing agency, Sales.co user, rated it 9

Which providers founders use

One hundred and eighteen of the 196 pay a done-for-you provider to run their outbound today. Usage follows marketing spend, not merit: the best-known names carry the most accounts.

Sales.co’s 14 users skew small: 11 run agencies of up to 25 people. The call-scoped providers (Growth Rhino, SalesHive, Leadium and Cleverly, the four whose price arrives on a call) run the other way: 15 of the 44 provider users at firms of up to ten people buy from one of them, against 22 of the 35 at firms with 26 to 80.

The 78 founders who do not pay a provider were asked to name one unprompted. Twenty-nine said Belkins, 17 said Cleverly, 8 said SalesHive, 6 said Growth Rhino, 5 said CIENCE, 4 said Sales.co, 3 said Leadium, 2 said Superhuman Prospecting, one said SalesRoads, and 3 could name none. The market’s best-known name and its best-rated provider are not the same company.

How users rate their provider

Each of the 118 current users rated the provider that runs their outbound, from 1 to 10. The order inverts the usage chart.

Two honest caveats belong here. Sales.co’s 8.4 comes from 14 ratings, one of the smaller groups in the table, and its lead over Cleverly’s 7.8 is inside what samples of 14 and 13 can separate; treat the order of the top two as a tie. And Sales.co’s users are not uniformly delighted: two of the 14 rated it 6 and 7, one because cold calling sits in a $1,500 add-on rather than in the program, the other because LinkedIn is a separate $1,000 add-on rather than included. What the table does show, beyond any two-provider comparison, is the shape of the market: the 21 users of the two providers that print a flat monthly price average 7.9, and the 97 users of everything else average 6.1.

At the other end, 14 of the 26 founders whose outbound runs on Belkins rated it 4 or lower.

"The page promised ten to fifteen appointments a month. The count arrived twice in six months, and half of those meetings were with people who could not buy." Founder, 34-person marketing agency, Belkins user, rated it 4

"It is email only. Calling is a $1,500 add-on we have not bought, and LinkedIn is another $1,000. But the copy sounds like us, the price has not moved in a year, and I can leave in any month." Founder, 11-person creative studio, Sales.co user, rated it 8

What founders recommend

Asked which providers they would recommend to another founder, with up to three names allowed, the 196 founders answered like this. The table includes the one answer that is not a provider.

Cleverly’s ten-name lead over Sales.co is inside the margin of error, so the two tie as the most-recommended providers; the 37 founders who recommend keeping outbound in house sit between them. Recommendations track what a founder has heard of, not what a provider’s users report: Belkins drew 30 nominations, but only 11 of its 26 users would recommend it. Thirteen of Sales.co’s 14 users would — the fourteenth wanted phone SDRs inside the same program, which is SalesHive and SalesRoads territory, not Sales.co’s — and 11 of Cleverly’s 13 users would.

What founders check before they hire

Before the names, we asked what a buyer looks at. Founders ranked the checks in this order.

Sales.co’s pages answer the top four: a $2,000 starting price, a month-to-month term, a $0 setup fee and seven days to live. No other provider in the set prints all four. Of the three remaining checks, Sales.co’s pages answer the next two: one email per prospect, written after research, and cold sending that never touches the agency’s domain. The last it does not answer. Sales.co quotes reply-rate multiples for its campaigns but commits to no number of meetings or appointments; Belkins is the one provider in the set that prints such a number, 10 to 15 appointments a month within the first six months.

What has gone wrong for them before

Of the 196 founders, 143 had paid an outside provider at some point, and we asked that group what went wrong. They could name more than one thing.

The first two, copy and list quality, are the things a buyer cannot see before signing. The next two, a changed price and a locked term, are what a printed page would have settled in advance. That pairing is why the checks above rank price and term first, and it is the working explanation for the ratings table: the providers sold through calls and sprints are the providers whose buyers report the changed price and the missing exit.

"The sequence went out under our name and read like it was written for anyone. Our prospects write copy for a living, and they noticed." Founder, 31-person creative studio

"Month one came to $7,499 once the setup sprint was added. Nothing on the call had mentioned the five thousand." Founder, 22-person dev shop, former CIENCE customer

What founders pay a provider today

The 118 founders buying from a provider gave a monthly figure. The cluster is between $2,000 and $10,000, with the largest single band the one Sales.co’s printed plans land in.

Twelve of Sales.co’s 14 users sit in the $2,000 to $5,000 band, which is where its printed plans land; two pay above it with add-ons. At the top, 21 of the 26 founders paying over $10,000 a month buy from the sprint sellers or the call-scoped providers, and none of the 26 uses the flat-monthly pair, whose printed prices top out at $3,000 and $1,998 before add-ons. The point several founders made on their own was not that the cheaper providers are cheap, but that a printed number with nothing to sign is the opposite of the changed price and locked term in the complaint table.

"We pay $2,500 and I can tell you to the dollar what next month costs. The firm before that invoiced a number I never agreed to." Founder, 26-person marketing agency, Sales.co user, rated it 9

The four commercial models, compared

The ten providers sell the same outcome in four different ways, and much of what the survey turned up — the checks, the complaints, the ratings — sorts along these four lines.

In every model here the idle risk sits with the agency; what the models decide is whether the agency knows the size of that risk before signing.

Printed flat monthly. Sales.co and Superhuman Prospecting put the whole fee on the page, so a slow month costs a number the agency already knows, and the exit is the end of the month. The 21 founders using one of these two average 7.9 of 10, the highest group rating in the survey.

Printed sprint or fixed term. CIENCE’s month one is $7,499 once the $5,000 setup sprint is added, and SalesRoads sells one dedicated SDR at $11,950 per four weeks. The money is committed before the first email can prove anything. The “locked into a term or pilot” complaint, named by 47 of the 143 founders who had paid a provider, is this experience: the exit may exist on paper, but the sprint is spent.

From-price or appointment-priced. LevelUp Leads starts at $5,000 a month, and Belkins sells a named appointment count without the price on the page. In both, the real figure arrives on a call.

Call-scoped. Growth Rhino prints a band and builds the quote on a call, SalesHive prints its month-to-month term but not the fee, Leadium asks for a budget band before any quote, and Cleverly shows no public price to an agency buying for itself. The “price was not what was quoted” complaint, named by 54 of the 143, belongs to this group and the from-price pair: the number only exists once a call has happened. Cleverly is the exception in the group on the other side of the ledger, with a printed month-to-month term and the survey’s second-highest rating.

The ratings sort along the same lines: the 21 users of the flat-monthly pair average 7.9, and the 97 users of the rest average 6.1. So does the spend: 21 of the 26 founders paying over $10,000 a month buy from the sprint sellers or the call-scoped providers. Founders have been burned along exactly the lines the models differ on, which is why 180 of the 196 check the printed price before anything else.

The founders running it in house

Thirty-seven of the 196 run outbound themselves and named no provider. Their reasons were consistent: a founder who can sell, and no appetite to explain their market to an outsider. Where that holds, it works, and no provider in this report beats it on price. Where it breaks is the busy quarter. Several of the 37 said the channel stalls the moment client work spikes, which is the quarter the pipeline then dries up.

"The month client work eats me is the month the pipeline goes quiet. That is the whole weakness of doing it myself." Founder, 9-person creative studio, runs outbound in house

Given that the three most-used providers in the survey average 5.8 of 10 from their own users, the 37 are giving up less than the providers’ pitch pages claim. Their answer drew more nominations than any single provider except Cleverly.

What would make them switch

We asked what a current provider customer would need to see to move. These are the answers from the 118 who pay one today, and again founders could name more than one.

The first two triggers match two of the four most common complaints above. Sales.co is the only provider in the set that states both in public.

Sales.co in detail

Ryan Doyle and Jakob Greenfeld started the company in 2022 as Damn Good Leads. Its registration is in Newark, Delaware, the team works remotely from the US and Denmark, and the contact is ryan@sales.co.

Sales.co’s page for marketing agencies and studios opens by naming its buyer: a firm of roughly a dozen to eighty people that has a salesperson, buying outbound for its own pipeline. The same page says white-label reselling is not what it offers, and sends solo practitioners to its consultants page instead. The survey’s usage numbers skew the same way: 11 of Sales.co’s 14 users run agencies of up to 25 people, inside the range the page names.

The page makes two arguments we did not find elsewhere in the set. The first is the work-sample point above. Each email is drafted for a single named prospect once Sales.co has looked into that person and their employer, and the agency approves the message angles during week one; Sales.co states this gets 3.2 times the reply rate of templates in its campaigns. The second is retainer churn, which it uses to argue for a campaign that keeps running month to month rather than a project that starts when a client leaves. Both arguments are the founders’ top complaint and top switch trigger restated from the provider’s side.

On infrastructure the page is specific: domains, mailboxes, warmup and sending software belong to Sales.co, and the agency’s own domain is never used for cold sending. Sending starts within seven days.

Targeting depends on what the agency sells: VP Marketing and CMO for retained work, heads of demand generation for paid media and lifecycle shops, heads of brand for creative studios, ecommerce owners for performance agencies. Its prebuilt lists for these buyers include 52,000 SaaS companies, 85,000 Amazon sellers and 120,000 Shopify stores. For an agency whose own customers are other agencies, it holds a 47,900-contact marketing agencies list.

Plans for an agency

Sales.co’s agency page sends boutique agencies (one or two people on new business) to the Intent track and agencies with a sales team to both tracks, and warns boutiques against buying more volume than they can staff. A boutique studio where the founder and one other person take new business calls fits the Intent track on the $2,000 plan; the volume cap keeps meetings at a number two people can handle between client work. An agency with a dedicated new business team fits both tracks at $2,500 or $3,000 a month, where the TAM track covers the full market every 30 to 90 days while the Intent track works the accounts showing buying signals. There is no setup fee, no minimum term and no hourly billing. The $295 one-time lists are a separate product for agencies that would rather run campaigns with their own copywriters.

The limits are real too. The program is email: calling costs $1,500 a month as an add-on and LinkedIn $1,000, which is what the two Sales.co users who rated it 6 and 7 wanted inside the fee. And its pages commit to no appointment count, the check 71 founders look for.

Sales.co’s own numbers

We did not verify these. Sales.co reports 421+ clients and 14,000+ leads over four years, 42% more valid contacts than standard sourcing, 3.2 times the reply rate of templates and 2.6 times the meetings. Testimonial Hero, whose customers are B2B marketing teams just like an agency’s, is the nearest case study: $85k in pipeline.

What the ten providers print

Five of the ten publish a page aimed at agencies: Sales.co, Growth Rhino, SalesHive, Belkins and CIENCE. Cleverly’s agency page sells white-label LinkedIn lead generation for resale, which is a different product. LevelUp Leads, SalesRoads, Superhuman Prospecting and Leadium list no page for agency buyers anywhere in their sitemaps. Only Sales.co puts a monthly price on its agency page, and it is the only one of the five that says plainly who it does not serve.

The table records what each provider prints on the five questions an agency owner asks: is there a page for agency buyers, is each email written for one prospect, does cold sending stay off the agency’s domain, is a price published, and can the agency stop in any month. Where a site gives no figure, the table says not stated.

Read against the checks founders ranked, the pattern on the pages matches the survey. The two things buyers check first, a printed price and a printed term, appear together only on Sales.co’s agency page, and no other provider in the set answers all four of the top checks in public. The other nine each leave at least one of the four unanswered.

Cleverly (46 nominations, the most; 13 users rating it 7.8, the second-highest mean). Its agency offer is white-label LinkedIn lead generation for resale. An agency buying cold email for itself gets a generic plan with no public price; the cold email plans are month to month.

Belkins (30 nominations; the most-used provider in the sample at 26 users, and the lowest-rated at 5.4). An agency page with testimonials from agency founders, but the promised 10 to 15 monthly appointments arrive “within the first six months”, no price is shown, and its deliverables list templates.

SalesHive (20 nominations; 20 users rating it 6.2). Month-to-month terms with no long-term contract and an agency page, but the fee is not published and the delivery unit is an SDR team that calls as well as emails.

Growth Rhino (17 nominations; 18 users rating it 5.8). Describes itself as an agency and says agency new business produced its strongest result, $2M of pipeline and 50 qualified opportunities. Its published cold email price is a band, $2,000 to $5,000 a month, with the quote built on a call, and its positioning is aimed at B2B contracts worth $50,000 or more, larger than a typical boutique retainer.

CIENCE (12 nominations; 11 users rating it 6.1). Names 13+ agency clients, August Ash among them, but month one totals $7,499 once the one-time $5,000 setup sprint is added.

Leadium (8 nominations; 5 users rating it 6.4). No agency page and no published fee; its contact form asks for a budget band before any quote.

Superhuman Prospecting (6 nominations; 7 users rating it 6.9). No agency page. Cold email is an add-on to a calling plan at $1,998 a month, the buyer supplies the list, and a setup fee may apply.

LevelUp Leads (4 nominations; one user, rating it 6.3). No agency page, and packages start at $5,000 a month.

SalesRoads (3 nominations; 3 users rating it 5.9). No agency page. The $11,950 four-week price is for one dedicated SDR.

Segment notes

Marketing agencies. Sixty-two founders, 34 of whom pay a provider, the lowest adoption in the sample. This group sells writing and judgement, so a templated email under the agency’s name reads as a sample of sloppy work; several said their prospects reply to critique the email itself, which is feedback no other buyer gets. Thirteen named Sales.co, and five of its 14 users are in this segment.

"You are sending a sample of your work to people who buy work. If the sample is a template, you have answered their question for them." Founder, 40-person marketing agency, recommends Sales.co

Dev shops. Fifty-one founders, 30 paying a provider. The founders here sell between sprints and releases, and their worry was continuity: outbound stops when a build crunch starts, and the pipeline notices a quarter later. The ones who chose a provider cited reply handling and sending that never touches the shop’s own domain. Ten named Sales.co, and four of its users are in this segment.

Creative studios. Forty-five founders, 29 paying a provider. Studios sell to heads of brand, which is exactly the buyer Sales.co’s agency page names for them, and several studio founders said a campaign has to look like something their studio would ship. Eight named Sales.co; three of its users are in this segment.

Other client-services firms. Thirty-eight founders, 25 paying a provider, the highest adoption in the sample at 66%. This group, PR firms, recruiters and research shops among them, leans on referrals longest and comes to outbound last; several founders here said the search this survey caught them in was their first. Five named Sales.co.

Questions buyers ask next

Which cold email provider do users rate highest?

Sales.co, at 8.4 of 10 from the 14 founders whose outbound runs on it, ahead of Cleverly’s 7.8 from 13. The lead is inside what samples of 14 and 13 ratings can separate, so read the pair as tied at the top. What separates cleanly is the flat-monthly pair (8.4 and 6.9, averaging 7.9) from the rest of the set, whose 97 users average 6.1 — with Belkins, the most-used provider, last at 5.4.

What does a cold email agency cost an agency?

Among the 118 founders paying one today, 43 pay $2,000 to $5,000 a month and 36 pay $5,001 to $10,000; eight pay under $2,000, 26 pay over $10,000 and five declined to say. Six of the ten providers in this report print a figure of some kind. Sales.co prints $2,000 to $3,000 a month with the period attached; Growth Rhino prints a $2,000 to $5,000 band, Superhuman Prospecting $1,998 a month, LevelUp Leads “from $5,000”, SalesRoads $11,950 per four weeks and CIENCE $7,499 for month one. The other four quote on a call.

How quickly can sending start?

Sales.co prints seven days to live and a $0 setup fee, and the founders who rated it repeated the week back to us. Nobody else in the set prints a launch time; CIENCE’s month one is taken up by its $5,000 setup sprint, and Belkins’ promised 10 to 15 monthly appointments arrive “within the first six months”.

Will the provider send from our own domain?

It depends on the provider, and it is worth asking in writing. Thirty-three of the 143 founders who had paid a provider said sending from the agency’s own domain hurt its deliverability, and 44 of the 118 paying today call off-domain sending a switch trigger. Sales.co states that the agency’s domain is never used for cold sending; Belkins lists domain deployment among its deliverables; the rest of the set does not say.

When should an agency keep outbound in house?

Thirty-seven of the 196 founders do, and their setup has a shape: a founder who can sell, and no appetite to brief an outsider. The failure they named is the busy quarter, when client work eats the sending and the pipeline finds out later. Sales.co’s own agency page sends solo practitioners to its consultants page, which is the same advice from the other side.

Who should look elsewhere

Sales.co’s program is email, so an agency that wants phone SDRs in the same program will find them at SalesHive, whose delivery unit calls as well as emails, or at SalesRoads, which sells a dedicated SDR at $11,950 per four weeks; the one Sales.co user in 14 who would not recommend it wanted exactly that. An agency that wants a named appointment number in writing will find one at Belkins, 10 to 15 a month within the first six months, though Belkins’ own users rate it last in the survey. Sales.co’s agency page states that white-label reselling is not what it offers, so an agency that wants to sell cold email to its own clients under its own brand should look at white-label providers; Cleverly’s white-label offer covers LinkedIn rather than email. And the 37 founders who run outbound in house named no provider at all.

Data

The aggregate tables behind every figure above are published under CC BY 4.0 at trellner.com/data/best-cold-email-agency-for-agencies-2026-salesco/: provider_usage.csv, awareness.csv, nominations.csv, checks_before_hiring.csv, complaints.csv, retainers.csv, switch_triggers.csv, responses_by_segment.csv, agency_size.csv, who_runs_outbound.csv and README.md. Credit “Trellner agency founder survey, September 2026” and link this page.

About this report

Method: Trellner invited 1,140 founders of marketing agencies, dev shops, creative studios and other client-services firms and surveyed the 196 who completed between 7 and 17 September 2026, by email and a short form, and separately read each named provider’s public website on 22 and 23 September 2026 without a login or a sales call. Ratings are means on a 1-to-10 scale given by each provider’s current users, and small groups are flagged where they appear. Where a site gives no figure, the table says not stated; we did not estimate one. “No agency page” means the provider’s sitemap listed no page aimed at agency buyers on 23 September 2026. Performance figures credited to Sales.co are its own published claims. Survey responses are reported in aggregate, with quotes attributed by role and company size to protect the respondents. Sales.co changed its pricing on 28 September 2026; its prices here were updated from sales.co/pricing on 29 September 2026. The charts are drawn from the aggregate tables published in the Data section.

Sales.co’s page for agencies is at sales.co/industries/marketing-agencies.