The Best Client Approval Tool for Email Marketers (2026)

Updated October 2026 · Pricing checked October 2026

Getting a client to approve an email before it sends sounds simple. In practice it usually means a forwarded test, a thread of conflicting comments, and a “looks good!” that nobody can prove later.

There are three kinds of tool people use to fix this, and they solve different problems. This page compares them, including where SendCleared fits and where it doesn’t.

Disclosure: this page is published by SendCleared. We’ve tried to be fair about what each option does well, and we link to each vendor so you can check current details yourself.

The short answer

• You send email campaigns for clients and need a clean, provable sign-off: an email-specific approval tool like SendCleared.
• You need to test how emails render in dozens of inbox and device combinations: a rendering tool such as Litmus or Email on Acid (now moving to Mailgun Inspect).
• You review lots of different asset types (video, PDFs, ads, web pages) as well as email: a general proofing platform such as Ziflow, Filestage or ProofHub.
• You send only a few campaigns and your clients are relaxed: a shared preview link plus a clear email may be enough.

Most agencies end up combining two of these, which is fine. They check different things.

What “client approval” should actually give you

Before comparing tools, it helps to be clear about the job. A good approval step gives you:

1. A frozen version. The client approves the exact email that will send.
2. Content checks first. Broken links and unresolved merge tags are caught before the client sees anything.
3. One place for feedback. Not a thread, not three channels.
4. A record. Who approved, which version, and when.
5. Low friction for the client. They shouldn’t need to learn a tool to say yes.

Judge every option below against those five.

Comparison at a glance

Swipe the table sideways to see every option →

Pricing changes often and third-party listings disagree. Figures above were checked in October 2026 against each vendor’s own pages; check them again before deciding.

The options in detail

1. SendCleared: email-specific QA and client approval

Best for: freelancers and small-to-mid agencies who send campaigns for clients and need a clear, provable yes before anything goes out.

SendCleared is built around one workflow. You add a client and get a unique test address, send your normal test from your ESP, and an automated check runs in about ten seconds across merge tags, links, alt text, spam triggers, UTM parameters and the unsubscribe and address essentials. You then share a branded approval link. The client sees the email at desktop and mobile widths and approves it or requests changes. The approval is logged with a name and a timestamp.

Where it’s strong: it covers the whole step between “I’ve finished building this and run a thorough QA” and “my client has approved it.” It works with any ESP that can send a test, and it’s priced for small teams, with a free tier and paid plans from $19/mo.

Where it falls short: it isn’t a rendering tool (although we’re exploring it). The approval page shows desktop and mobile widths, not how the email displays in Outlook, Gmail or Apple Mail. It’s also email-only. If you review video, PDFs or ads, you’ll want something broader alongside it.

2. Litmus: rendering previews plus enterprise collaboration

Best for: in-house teams with high email volume where rendering across many email clients is a recurring problem.

Litmus is best known for inbox rendering previews across 100+ client and device combinations, plus analytics and collaboration features. Litmus Proof, its review feature, is described in Litmus’s help documentation as available on Enterprise plans. It supports comments, resolving feedback, an approval button and version browsing, and reviewers outside your team can take part by email or a shared link.

Where it’s strong: rendering fidelity, and a broad platform for large teams.

Where it falls short for agencies and freelancers: pricing and fit. Review sits on the Enterprise tier, which has no public price and is sold through sales, so it’s a larger commitment than most small agencies want just for approvals. See our full Litmus comparison.

3. Email on Acid / Mailgun Inspect: rendering and code testing

Best for: email developers and teams building templates from code who need rendering previews, spam and accessibility testing.

Email on Acid offers previews across 100+ clients and devices, plus spam testing and code analysis, and has long been the more affordable alternative to Litmus. It is being succeeded by Mailgun Inspect, with existing subscribers moving over from June 2026, so plans and pricing are changing.

Where it’s strong: testing depth at a lower price than Litmus.

Where it falls short for agencies and freelancers: it’s built around the person running the tests, not around a client approving the result. See our full Email on Acid comparison.

4. Ziflow, Filestage and ProofHub: general proofing platforms

Best for: agencies and marketing teams reviewing many kinds of creative (video, PDFs, designs, web pages, ads) and managing multi-stage approvals.

These tools are built for review and approval in general. Clients and stakeholders can comment directly on a file and approve it, and they typically offer workflow stages, reviewer groups and integrations. ProofHub is closer to a project management tool with proofing built in, while Ziflow and Filestage are dedicated proofing platforms. Both Ziflow and Filestage offer limited free plans (Filestage’s covers one active project and a monthly cap on new files), with paid plans starting at around $199/mo. ProofHub is cheaper, from about $45/mo billed annually with a flat price rather than per user.

Where they’re strong: breadth. One tool for every asset type, with flexible multi-stage review.

Where they fall short for email marketers: they aren’t email-specific. They won’t automatically catch an unresolved merge tag or a missing unsubscribe link, and getting a real email into them usually means uploading a screenshot, HTML file or link rather than reviewing a live test send. For teams whose main work is email, that’s extra steps and no automated content checks. The dedicated platforms are also pitched at teams reviewing many projects, which can be more than a small email-focused agency needs.

5. ESP preview links and Slack threads: the default workaround

Best for: low-volume senders with relaxed clients and low stakes.

Many ESPs offer a shareable preview link or a test send, and plenty of agencies approve over email or Slack. It costs nothing and needs no setup.

Where it falls short: test emails often show placeholder data and look like tests, feedback scatters across threads, and there’s no reliable record of what was approved. It works until a client says “I never approved that.” For the full breakdown, see How to Send a Test Email Your Client Can Actually Review.

How to choose

Common questions

Related reading:
The Email QA Checklist for Agencies and Freelancers · SendCleared vs Litmus · Email on Acid vs SendCleared · How to Send a Test Email Your Client Can Actually Review