Best Email Deliverability Agencies to Fix Your Infrastructure

Most deliverability problems look like marketing problems at first. Open rates slide, a campaign underperforms, someone rewrites the subject lines. Then a customer mentions your emails have been landing in spam for weeks, and it turns out the cause was never the copy. It was a DKIM key that stopped aligning after a platform change, a shared domain carrying both cold outreach and password resets, or a mail server sending faster than Gmail will accept.

That kind of problem is what a deliverability agency is for. This guide compares nine options that fix the sending setup itself, not just report on it, and it starts with the question most roundups skip: whether you need one at all. If you search for this topic you will find plenty of “best agencies” lists, and many are published by agencies that rank themselves first or by software vendors selling something adjacent, so read them with that in mind.

How this list was put together. We compared each firm on what it publishes: its services, whether it does the implementation or only advises, what it charges, and what it shows as proof. We have not hired these firms, so nothing here is a test result, and the results quoted are the firms’ own. Prices were verified in November 2026 on each firm’s own site.

The best email deliverability agencies at a glance

Agency	Best for	Fixes it for you?	Published pricing
Email Industries	Teams on an ESP who want a set price and a full audit	Yes, implementation is an add-on on the audit package	$999/mo for 2 months, or from $4,199 total
Unspam	Teams already using Unspam’s testing or DMARC tools	Yes, including managed IP warm-ups and delisting	Audits typically $1,000 to $4,000; retainers from around $1,500/mo
MailSoar	Recovering from a serious inbox placement drop	Yes, its Fix service is hands-on	Quote only
Designmodo	Postcards users who want one starting point for design and delivery	Yes, through its partner MailSoar	Quote after a free discovery call
Postmastery	Running your own mail servers	Yes, including turnkey MTA setup	Quote only
Word to the Wise	Blocklist emergencies and hard, senior-level cases	Advises and works alongside your team	Quote only
InboxArmy	Fixing deliverability as part of a wider email program	Yes	Basic audits around $2K to $5K
MailAdept	Ongoing care across several sending domains	Works with your team on a subscription	Per domain, 4-month minimum
MailBrace	Done-for-you setup, and cold email infrastructure	Yes	Custom plans only

What “fixing the infrastructure” actually covers

Deliverability work splits into two halves. One is behavior: who you email, how often, and whether they want it. The other is infrastructure, the technical layer that decides whether mailbox providers can trust a message before anyone reads it. When you evaluate an agency, ask which of these layers it will change itself:

• Authentication. SPF, DKIM, and DMARC set up and aligned with your visible From domain, with DKIM signing on your own domain at every service that sends for you. BIMI and MTA-STS come on top of that.
• Domain structure. Separate subdomains for marketing and transactional mail, so a bad campaign cannot take password resets down with it, and cold outreach kept well away from your main domain.
• IPs and warm-up. Choosing between shared and dedicated IPs, then ramping volume gradually on anything new, since a new IP or domain starts with no reputation.
• Mail server configuration. Reverse DNS, TLS, and connection and throttling settings per mailbox provider. If you use an ESP, it handles most of this for you. If you run your own server, this layer is yours.
• Reputation repair. Blocklist removal, complaint reduction, and list cleaning, followed by a controlled return to full volume.

Several of these stopped being optional. Google’s sender guidelines require SPF or DKIM, valid reverse DNS, TLS, and a spam rate below 0.3% from all senders, and anyone sending 5,000 or more messages a day must have both SPF and DKIM, plus DMARC. Outlook.com now rejects non-compliant high-volume mail outright rather than filtering it to Junk.

Do you need an agency?

Often, no. A lot of infrastructure problems are a DNS record or an ESP setting away from being fixed, and an audit will not tell you anything a free checker could have. Try this first:

1. Check your records. Run your domain through a free DMARC checker, SPF checker, and DKIM checker. Our guide to email marketing for Bootstrap developers explains what each record should look like.
2. Turn on custom DKIM at your ESP. Signing with your own domain rather than your provider’s is a common fix, and it survives forwarding where SPF does not.
3. Read your DMARC reports. They name every service sending as your domain and show which ones fail. Our DMARC monitoring guide walks through this.
4. Clean your list. Stop mailing people who have not engaged in months, and remove addresses that bounce.

Bring in a specialist when those steps do not move the numbers, or when any of these apply: you are on a blocklist and your removal request was denied or the listing came back; placement collapsed at one provider and you cannot say why; you are moving ESPs or adding dedicated IPs with real revenue at stake; or you run your own mail servers and nobody on the team has tuned one before. The test is simple. If the cost of a month of misdelivered email is larger than the cost of the engagement, hire someone.

The agencies, reviewed

Email Industries

Email Industries is the most transparent option here on price, and the one to start with if you send through an ESP and want to know what you will pay before the first call. It joined Ziff Davis in 2025 and also makes Alfred, an email validation and threat detection service.

Infrastructure scope. Its audit and remediation service covers authentication and DNS health, IP and domain reputation, blocklists, and inbox placement testing at Gmail, Outlook, and Yahoo, followed by fixing SPF, DKIM, and DMARC misconfigurations. It also handles ESP migrations and offers ongoing monitoring on retainer.

Pricing. Two published packages. Deliverability Foundations is $999/mo for two months and includes SPF, DKIM, and DMARC setup, 15 inbox placement tests, basic monitoring, and hygiene for 25,000 addresses. Deliverability Readiness and Optimization starts from $4,199 total and covers a full audit of two domains or subdomains, 25 placement tests, and hygiene for 75,000 addresses.

Watch for. On the larger package, implementation, remediation, and delisting are add-ons, so confirm the full price of the fix and not just the audit. Proof it publishes: a case study reporting WithMe’s inbox placement rising from 82.3% to 93.7%.

Unspam

Unspam is best known for its email testing tools, and its consulting service suits teams that already use them, since the consultants and the data sit with one provider. If you use its DMARC monitoring or inbox placement testing, this is the shortest route to a person who can act on the results. Its page says the consulting is run with the Email Industries team, so ask how the two offers differ for your case.

Infrastructure scope. The widest published infrastructure list here: SPF, DKIM, DMARC, BIMI, and MTA-STS setup with weekly review of DMARC reports; custom infrastructure for new sending domains and scaling; managed IP warm-ups; delisting at Spamhaus, Barracuda, SpamCop, UCEPROTECT, and provider-specific lists; and recovery work on Gmail and Outlook reputation drops. It also offers a fractional deliverability team for ESPs and very large senders.

Pricing. No set packages. Its page says a standalone audit typically runs $1,000 to $4,000 and retainers usually start around $1,500/mo, scaling with volume and complexity.

Watch for. Those are typical ranges rather than a price list, so get your scope quoted. Proof it publishes: client testimonials, including a healthcare marketing director describing a move from nearly no delivery to almost perfect scores.

MailSoar

MailSoar does deliverability and nothing else, which makes it a strong pick when email is a major revenue channel and placement has already collapsed. It sells four services that map to where you are: Find (audit), Fix (recovery), Grow (scaling), and Run (monitoring).

Infrastructure scope. The Fix service is implementation rather than recommendations: its consultants work inside your existing ESP, CRM, and DNS on SPF, DKIM, and DMARC alignment, sending domain and IP setup, blocklist removals, list work, and warm-up, doing authentication and infrastructure first. The Find audit takes about 10 days and produces a 30 to 40 page report plus a one-hour delivery call.

Pricing. Not published. The audit is fixed-scope and quoted after a short call.

Watch for. The Fix page gives two timelines, “2 to 6 weeks” in one place and “around 12 weeks” in another, so ask which applies to you. Proof it publishes: 500+ companies and a 4.9/5 rating across 200+ Trustfolio reviews, plus named case studies such as True Classic going from 30% to 95% inbox placement. These are the firm’s own figures.

Designmodo

Designmodo makes the Postcards email builder rather than running a deliverability practice of its own, but it offers deliverability consulting directly on its site, and it suits Postcards users who want to start with a company they already deal with. The work itself is done by its partner, MailSoar, so go to Designmodo for the introduction and expect MailSoar’s team on your reports.

Infrastructure scope. Audits, SPF, DKIM, and DMARC moved safely to enforcement, sending domain architecture, dedicated versus shared IPs, warm-up schedules, blocklist removal, and ongoing monitoring.

Pricing. No published prices. You book a free discovery call and get told what the fix would cost.

Watch for. If you do not use Postcards, there is little reason not to contact MailSoar directly. Its page’s satisfaction and client figures are also MailSoar’s own, not separate results.

Postmastery

Postmastery is the most literal answer to “fix my email infrastructure”. Based in the Netherlands, it describes itself as a vendor-independent system integrator, and it is the only firm on this list built around the mail server layer. If you run your own sending platform, or you are an ESP, start here.

Infrastructure scope. Email infrastructure setup from system design to tuning for mailbox provider policies, including turnkey on-premises systems. It works with PowerMTA (it is a Bird authorised channel partner), Postfix, KumoMTA, GreenArrow, and Halon. Its deliverability audit goes deeper into the technical layer than most: DNS, reverse DNS, and HELO setup, TLS, MTA configuration, DKIM key rotation, and analysis of SMTP logs for throttling and rejections. It also sells outsourced delivery monitoring and its own analytics console.

Pricing. Not published; you request a quote.

Watch for. If you send through a hosted ESP, most of this depth has nothing to work on, and a firm focused on your ESP setup and list may suit you better, though Postmastery does audit ESP customers too.

Word to the Wise

Word to the Wise is the senior advisor on this list. Founded in 2001 by Steve and Laura Atkins and now based in Dublin, it stays deliberately small, and other email companies use it as well: its consulting page lists tier-three escalation for in-house experts and policy work for ESPs.

Infrastructure scope. Spamhaus listings, blocking, and other email disasters; fixing technical and authentication issues as part of longer delivery engagements; and expert witness work on email and DNS. It can also embed a policy expert in your team’s Slack.

Pricing. Not published. You email them with your situation, and they schedule a call.

Watch for. Strategic and delivery engagements often run three to six months, and the firm says plainly that a quick silver bullet is rare. This is an advisor who works with your team, so you need someone in-house to carry out the changes. It is overkill for a missing DKIM record and exactly right for a blocklisting nobody else could resolve.

InboxArmy

InboxArmy is a full-service email marketing agency with a deliverability practice, so it suits teams whose real problem is broader than infrastructure and who would rather have one partner for everything.

Infrastructure scope. Authentication and DNS review, domain strategy that separates marketing from transactional mail, structured IP and domain warm-up, blocklist remediation, inbox placement monitoring, list cleaning, and full ESP migrations, across more than 40 ESPs.

Pricing. It says basic audits may start around $2K to $5K, with deeper multi-domain audits costing more. Ask for the remediation price separately.

Watch for. Deliverability is one service among many here, so ask who will actually work on your account and how much of their time goes to deliverability. Proof it publishes: a real estate client whose open rates rose from under 5% to 20 to 40% after SPF fixes, list rebuilding, and a controlled warm-up.

MailAdept

MailAdept sells deliverability as a subscription rather than a project, which suits SaaS companies and outbound teams whose setup keeps changing. Each new tool, domain, or DNS change is a chance for authentication to break again, and a one-off audit will not catch that. It is built by Mailwarm Inc., a Y Combinator S20 company.

Infrastructure scope. Audits of domains, authentication, routing, and provider setup; help resolving SPF, DKIM, DMARC, BIMI, domain structure, and blocklist issues; and more than 12 automated checks per domain every day, with a dedicated expert embedded in your team. It covers marketing, transactional, and outbound email.

Pricing. Custom and based on your number of domains, billed monthly with a four-month minimum. A free audit comes first.

Watch for. The commitment. Four months is sensible for reputation work, but it is more than you need for a contained fix. Its wording is also “help your team resolve”, so check what its experts change themselves.

MailBrace

MailBrace is a consultancy and a practical choice for teams that want the setup done for them, especially if cold email is part of the picture, since it also builds outbound infrastructure: domains, inboxes, authentication, and warm-up, kept apart from your marketing reputation.

Infrastructure scope. SPF, DKIM, and DMARC across your domains, sender reputation repair, inbox placement testing at Gmail, Outlook, and Yahoo, list cleaning, and ongoing monitoring, which it says is part of every service.

Pricing. Custom plans based on list size and volume, after a free audit.

Watch for. It publishes less proof than the others here, mostly short testimonials, so ask for references from senders of your size.

How to choose

• You send through an ESP and want a known price: Email Industries.
• You already use Unspam’s tools: Unspam.
• You build your emails in Postcards: Designmodo.
• Your inbox placement has already collapsed: MailSoar or Email Industries, and ask each for the price of implementation, not just the audit.
• You run your own MTA, or you are an ESP: Postmastery.
• You are on a blocklist and normal requests have failed, or your own experts are stuck: Word to the Wise.
• You also need campaigns, templates, or a migration handled: InboxArmy.
• You have many domains and a setup that keeps changing: MailAdept.
• You want cold email infrastructure built properly: MailBrace or MailAdept.

If what you need is software your own team can use instead of a consultant, that is a different purchase. Tools such as Unspam’s inbox placement testing, Folderly, and EmailConsul give you the data, but your team does the fixing.

What to ask before you sign

1. Who does the implementation? Many engagements end with a report. Ask whether their people will change your DNS and ESP settings, or whether your team will.
2. What is the price of the fix, not just the audit? Get remediation and delisting costs in writing.
3. What access do you need, and who will have it? Expect requests for DNS, your ESP, Google Postmaster Tools, and Microsoft SNDS. Use individual accounts you can revoke, and remove them when the work ends.
4. How will you measure success? Agree on a baseline before work starts, and look at several signals: placement tests, provider reputation data, complaint rates, and revenue from email. Open rates alone are unreliable because of Apple’s Mail Privacy Protection.
5. What happens if nothing improves? Ask for their process and any exit terms.
6. Can you hand it back? A good engagement ends with documentation your team can maintain.

Be wary of a few things. No one can guarantee an inbox placement figure, because mailbox providers decide and filter partly on how your recipients behave. Be careful too with anyone who offers delisting without asking why you were listed: if the cause is still there, you will likely be listed again. And anyone whose main fix is a new domain may just be moving the problem, because reputation problems tend to follow the same sending behavior.

Wrapping up

Start with the free checks, because some problems end there. If they do not, pick the firm that matches the layer that is actually broken: Email Industries for ESP senders who want clear pricing, Unspam if you already use its tools, MailSoar for a hands-on recovery, Postmastery if you run your own mail servers, and Word to the Wise for the cases nobody else has solved. Whichever you choose, get the price of the fix and not just the audit, and make sure your team can keep it running afterward. To watch for new problems once things are fixed, our guide to DMARC monitoring is the next step.

FAQ

What does an email deliverability agency do?

It diagnoses why your email lands in spam or gets blocked, then fixes the causes. That usually means auditing SPF, DKIM, and DMARC, your domain and IP setup, your reputation with mailbox providers, and your list practices, then correcting what is wrong, handling blocklist removal, and warming up new domains or IPs.

How much does email deliverability consulting cost?

Many firms only quote after a call, but some publish figures. Email Industries lists $999 a month for two months for its foundations package and from $4,199 for a full audit package, with implementation as an add-on on that package. InboxArmy says basic audits may start around $2,000 to $5,000. MailAdept charges per domain with a four-month minimum. Prices verified in November 2026.

How long does it take to fix email deliverability?

Technical fixes like DNS records can take days, but reputation recovers more slowly because it depends on sending behavior over time. Firms give ranges from a few weeks to several months: MailSoar’s recovery service quotes 2 to 6 weeks in one place and around 12 weeks in another, and Word to the Wise says its delivery engagements often run three to six months.

Can a deliverability agency guarantee inbox placement?

No. Mailbox providers make that decision, and they weigh how your recipients respond as well as your technical setup. An agency can fix your infrastructure and improve your odds substantially, but treat a guaranteed placement percentage as a warning sign.

Do I need an agency to set up SPF, DKIM, and DMARC?

Not usually. If you send through an ESP, it provides the records and free checkers can confirm they work. An agency earns its fee when you have many sending services to align, need to move safely to a DMARC policy of p=reject, or have a reputation problem that correct records alone will not solve.

What is the difference between an email deliverability agency and a deliverability tool?

A tool shows you the problem, through inbox placement tests, reputation data, or DMARC reports, and your team does the fixing. An agency supplies the people who interpret that data and, depending on the contract, make the changes. Many teams start with a tool and hire help only when they cannot move the numbers themselves.