# 5 best email tools for agencies managing multiple brands in 2026

Canonical: https://brew.new/blog/best-email-tools-for-agencies
Author: Philip Sørensen
Published: 2026-10-19
Updated: 2026-10-19

Brew publishes this comparison. We reviewed the linked product documentation on October 16, 2026; this is a documentation comparison, not a claim of hands-on testing of every platform. Check current plan limits on the vendor's pricing page.

It's Thursday afternoon, and two clients have sent feedback on campaigns due out tomorrow. One wants the offer higher in the email. The other approved the copy but attached a newer logo. Your designer is already on next week's work, and the account manager needs to know which drafts are ready for another review.

For an agency, email software shows up in the hours you bill. The subscription is one cost. Passing feedback between people and checking that each final version still matches the right client is the bigger one.

Our first pick for agencies managing several brands is Brew, because its agent builds each client's emails from that client's brand and your team reviews them in one place. Klaviyo, ActiveCampaign, Mailchimp and HubSpot come up when your clients already run on them, or when the work you sell is mostly automation or CRM.

## The tools and the work they fit

| Rank | Tool | Best fit for an agency | Client brands |
| --- | --- | --- | --- |
| 1 | Brew | Producing and reviewing on-brand emails for many clients | One brand workspace per client: 10 on Growth ($99/mo), 50 on Pro ($249/mo) |
| 2 | Klaviyo | Running campaigns for clients already on Klaviyo | One Klaviyo account per client |
| 3 | ActiveCampaign | Reselling and maintaining client automations | Client accounts through the partner program |
| 4 | Mailchimp | Working across clients who already send with Mailchimp | Client accounts connected to the Mailchimp & Co dashboard |
| 5 | HubSpot | Email as one part of a CRM implementation | One HubSpot portal per client |

## 1. Brew: every client's brand in one workspace

[Brew](/agencies) is fully agentic. You describe the campaign, and Brew's agent designs the finished email from that client's brand, sends it from the client's domain and builds the automation around it. Each client is a separate brand with its own design system, sending domains and contacts. Brew learns a brand from the client's website, and you can add their guidelines, logos and past emails.

Review happens on the email itself. Clients comment on the exact block they want changed, your team edits live, and everyone sees the same version. Nobody compares screenshots of different drafts. If the client's designer works in Figma, paste a frame link and Brew turns it into an editable email in that client's brand.

LeadGen Data replaced Stripo with Brew. When a client rebranded, its email lead built the client's new four-email flow in under an hour. The [LeadGen Data story](/customers/leadgen-data) has the details.

Growth includes 10 brand workspaces for $99 a month, and Pro includes 50 for $249 a month. Each plan also has monthly limits on AI credits and sends (Growth: 10,000 credits and 50,000 sends), so compare them with the volume your clients need. See [pricing](/pricing).

If a client insists on keeping their own sending platform, you can still build in Brew and export the email as a template to Klaviyo, HubSpot, Mailchimp, Brevo and eight other platforms.

Before you invite clients in, agree who reviews the work and who can schedule the send. A shared workspace makes review easier, but someone at the agency still owns the final decision.

## 2. Klaviyo: for clients already on Klaviyo

Klaviyo runs the [K:Partners program](https://www.klaviyo.com/partners/become-a-partner) for agencies, consultancies and developers that run Klaviyo for clients. Its AI agent, [Composer](https://help.klaviyo.com/hc/en-us/articles/52308788113307), drafts campaigns from the brand voice, colors, fonts and past sends in each account. Klaviyo notes that brand-new accounts with little context get weaker results.

That makes it a fit for clients whose store data and send history already live in Klaviyo. Composer works inside one client's account at a time, and your team finishes each draft in Klaviyo's editor.

Choose it if your clients are ecommerce brands that already run on Klaviyo and need SMS next to email.

See how it compares: [Brew vs Klaviyo](/compare/brew-vs-klaviyo).

## 3. ActiveCampaign: for agencies reselling automation work

ActiveCampaign's [partner program](https://www.activecampaign.com/partner) lets agencies resell accounts at a discounted rate or refer clients for a commission. The same page offers white-labeling and invoicing clients on your own terms, though white-label partners cannot also earn referral commissions.

It suits agencies whose retainer is building and maintaining customer journeys.

Choose it if you want to resell or white-label the email platform under your agency's name.

See how it compares: [Brew vs ActiveCampaign](/compare/brew-vs-activecampaign).

## 4. Mailchimp: for an existing base of Mailchimp clients

The [Mailchimp & Co dashboard](https://mailchimp.com/help/getting-started-with-mailchimp-and-co/) lets agencies [connect client accounts](https://mailchimp.com/help/connect-client-accounts/), with each client's owner approving the request. It helps when much of your client work already runs on Mailchimp.

Joining the program doesn't change the product plan each client pays for, so check which features their plan includes before you promise them.

Choose it if your clients stay on Mailchimp and you only need agency access to their accounts there.

See how it compares: [Brew vs Mailchimp](/compare/brew-vs-mailchimp).

## 5. HubSpot: for agencies that own the CRM too

HubSpot's [Solutions Partner Program](https://www.hubspot.com/partners/solutions) is for agencies and consultancies that implement HubSpot for clients. It belongs on this list when email is one part of a larger project that includes CRM setup and sales handoffs.

In that case, judge the platform against the whole service you sell, not the newsletter alone.

Choose it if you are implementing HubSpot's CRM for the client and email comes with it.

See how it compares: [Brew vs HubSpot](/compare/brew-vs-hubspot).

## Compare a month of client work

Pick a recent month and count the campaigns your team produced, including revisions and the steps to get each one approved. During the trial, repeat enough of that work to see whether the new process removes tasks or only moves them.

Track production time separately from time spent waiting on client feedback, so you know which problems software can fix. If producing consistent work across brands is where the hours go, try Brew with two clients whose brands look very different before you roll it out across the agency.

## Frequently asked questions

### How many client brands can I manage in Brew?

The Free plan includes 3 brand workspaces, Growth includes 10 and Pro includes 50. Enterprise plans have no limit. Each brand has its own design system, domains and contacts.

### Can clients review emails without an account on our ESP?

Yes. In Brew, you invite clients to their brand, and they comment on individual blocks of the email while your team edits. They need a Brew login, not an account on your ESP. Brand access also lets them edit and send, so agree who sends.

### Can we build in Brew and send from the client's existing platform?

Yes. Brew exports a finished email as a template to Klaviyo, HubSpot, Mailchimp, Brevo, Braze, Iterable and other supported platforms. The export creates a template and sends nothing. Audience, scheduling and reporting stay in the client's platform.