An MSP that looks at Zimbra is usually weighing two things: a mature mail, calendar and contacts suite it can run on servers it controls, and a partner program that lets it sell that suite to clients. Before you quote Zimbra across a 200-mailbox client book, know what the program asks of you: its partner terms assume you host the software yourself. This guide sets that path next to Atriomail, a hosted email platform you buy per mailbox and resell at your own price, so you can decide which commitment your business should take on.

Every Zimbra figure below was checked in September 2026 and names its source. Where Zimbra publishes no number, such as BSP per-mailbox rates, we say so.

Table of Contents

Key Takeaways

PointWhat it means for you
Zimbra BSPs host the software themselvesAnyone hosting Zimbra mailboxes for multiple third parties must join the BSP program, where licenses are rented, not bought
The entry minimum is $300 a monthAuthorized BSPs commit to at least $300 (or €225) a month; Silver, Gold and Platinum require $3,000, $10,000 and $25,000. Per-mailbox rates sit in a price book shared with approved partners
No free official build of current ZimbraZimbra stopped publishing free binaries from version 9; community builds and the free Carbonio Community Edition from Zextras come with community support only
WHMCS needs a third-party moduleModulesGarden's Zimbra and Carbonio Email module is listed at $15.95 a month or $129.95 a year, on top of licenses and servers
What Atriomail does instead$1.39 per mailbox per month with 15 GB included, no minimum and no long-term contract, and its own WHMCS 9 module. It sells mailboxes only: no calendar or contact sync

Compare the commitment before you compare features. Atriomail has no monthly minimum and no long-term contract: $1.39 per mailbox with 15 GB included, billed monthly from the first mailbox you create.

Create your account   See pricing

Three Ways MSPs Sell Zimbra Email

Zimbra reaches a small reseller in three shapes, and each one carries different obligations:

  • Join the BSP program and host Zimbra yourself. Zimbra's Business Service Provider Program Guide (updated March 2025, checked September 2026) requires any partner that hosts Zimbra mailboxes for multiple third parties to join the program, and bars service providers from hosting perpetual licenses bought from a distributor or value-added reseller. You run the servers; Zimbra rents you the licenses.
  • Resell another host's Zimbra service. Some hosting companies run Zimbra and let others resell it. Mission Critical Email, for example, offers a 20 percent discount off its retail rates with a $500 monthly minimum (smaller commitments get less), gives resellers domain admin access, and expects them to handle their own customer support (Mission Critical Email's Zimbra reseller program page, checked September 2026).
  • Run a free build yourself. Zimbra's own open-source FAQ (updated August 2023) says Zimbra 9 binaries are only available with a Network Edition license. Community builders compile the released source instead. Carbonio Community Edition from Zextras is free under the AGPL v3 license with community support only (Zextras' Carbonio CE page, checked September 2026).

The first and third paths put a mail server on your books; the second puts another reseller's minimum between you and the software. The explainer on how reseller email hosting works covers the wholesale basics, and the guide to selling email without owning the mail infrastructure explains the hosted model. Atriomail is in that hosted group: you buy mailboxes wholesale, with no partner minimum, and set your own resale price.

The BSP Program: What You Commit To

Zimbra's BSP Program Guide lists four partner levels, each with a minimum monthly spend. The higher Silver and Gold minimums applied to new partners from January 2025 and to existing partners from January 1, 2026.

BSP levelMinimum monthly spendSupport level
Authorized$300 / €225Zimbra Standard support
Silver$3,000 / €2,250Zimbra Premier support
Gold$10,000 / €7,500Zimbra Premier support
Platinum$25,000 / €18,500Zimbra Premier support

According to the same guide, BSP terms run on the calendar year, every agreement carries a 90-day cancellation policy, and licenses are ordered through an authorized aggregator. Every provisioned mailbox is billable, open or closed, until it is deleted, and billing follows the highest usage in the month; domains, aliases and distribution lists are not billed. Every licensed server must run Zimbra's usage reporting tool, at least one employee must be Sales Certified, you must support your own customers by email and phone, and you must stay on the latest supported version.

A small book feels the floor first. At a $5.00 resale price, the $300 Authorized minimum equals the revenue from 60 mailboxes, before you have paid for a single server. The guide to how usage-based email pricing scales with a reseller's book shows why a floor matters most while a book is growing.

Atriomail answers the same commercial question without a floor. You pay $1.39 per mailbox per month with 15 GB included, billed monthly, with no minimum number of mailboxes and no long-term contract, so you can start with a single client mailbox. One rule is the same on both sides, and worth knowing: an Atriomail mailbox is also billed until it is deleted, and deactivating it does not stop the charge.

Running the Servers Yourself

Hosting Zimbra means sizing hardware to Zimbra's published requirements. The Zimbra Daffodil (version 10) single-server installation guide (checked September 2026) asks for a minimum of 8 GB of RAM in production, 100 GB of free disk for software and logs plus whatever the mail itself needs, on a 64-bit Red Hat family or Ubuntu LTS server. Carbonio Community Edition asks for more: Zextras' requirements page lists 16 GB of RAM as the minimum and 32 GB as recommended for a single server.

The hardware is the part you can price in advance. The recurring work is harder to quote: patching, the upgrades a BSP must keep current on, backups, spam filtering and monitoring. If your team bills Linux administration by the hour, multiply that rate by the hours you expect each month and put the result in the quote. The comparison of Plesk-hosted client mail against white-label hosting shows similar server-side costs, and since Zimbra's program makes email and phone support your job, see building a support process for an email reselling business.

On Atriomail there is no mail server for you to size, install or upgrade. You add client domains and mailboxes in the control panel, every mailbox comes with 15 GB and webmail, and clients connect Outlook, Thunderbird or their phone's mail app over IMAP, POP3 and SMTP with encrypted connections. The trade is control over the stack: outgoing mail is delivered through Amazon SES on shared infrastructure, so bulk and cold email are banned to protect the sending reputation every customer shares.

Provisioning Zimbra From WHMCS

The WHMCS module we found for Zimbra is a third-party product: ModulesGarden's Zimbra and Carbonio Email for WHMCS. Its product page (checked September 2026) lists $15.95 a month or $129.95 a year, with a one-time source code license also offered. It supports WHMCS 8.10 through 9.0, Zimbra 8.5 and later, and Carbonio 24.5 and later. It creates, suspends and terminates accounts, changes packages and passwords, lets clients manage accounts, aliases and distribution lists, and supports WHMCS metric billing.

That is a capable module, and it covers older WHMCS versions than Atriomail's does. It is still a separate subscription on top of the license rental and the servers you remain responsible for. If WHMCS is not your billing system, the piece on connecting an email platform to your own portal through its API covers the other route.

Atriomail publishes its own WHMCS module, version 3.1.1, which requires WHMCS 9 and is downloaded from the Plugins page in the Atriomail control panel. It handles Create, Suspend, Unsuspend, Terminate and Change Package. Clients add mailboxes, 5 GB storage blocks, aliases and a catch-all in the WHMCS client area, and those additions become recurring WHMCS charges at the prices you set. Two conditions travel with that: changes made in the Atriomail panel or through the API do not sync into WHMCS billing, and the recurring charges the module creates are titled "AtrioMail mailboxes".

Onboarding Each Client Domain

On Zimbra, each client domain is set up at two ends. The Zimbra wiki's article on configuring DKIM signing (checked September 2026) has an administrator generate each domain's DKIM key on the server with the zmdkimkeyutil command, then publish the resulting TXT record at the domain's DNS host. MX, SPF and DMARC go in at the DNS host too. None of that is hard for a Linux administrator; the key generation simply happens on a server you run.

In Atriomail, every domain has a DNS Setup dialog listing the MX, SPF and DMARC records, plus the DKIM key and Amazon SES verification records once they are generated, each with a copy button. If the client's DNS is on Cloudflare or Namecheap, you can connect that account, let Atriomail import its domains, and then add the domain: once it clears the security check, Atriomail writes MX, SPF, DMARC, autodiscover, autoconfig and the DKIM key into the zone. Writing the MX moves that domain's mail, so add it only when you are ready to switch, and the SES verification records are still added by hand. The email domain management guide explains the records.

Moving existing client mail uses Atriomail's built-in IMAP migration, which has no charge. It copies mail from any server that allows IMAP sign-in with a password, keeping folders and original dates, but it moves mail only: calendars and contacts do not come across, which matters for clients who have lived in Zimbra's calendar. Bulk jobs need each account's own password. The agency playbook for sequencing email migrations covers planning a whole client book.

Zimbra vs Atriomail for Resellers

DimensionZimbra (BSP, self-hosted)Atriomail
Price per mailboxRented through an aggregator at price-book rates that are not published$1.39 per mailbox per month
Minimum and contract$300 a month at Authorized; calendar-year term with a 90-day cancellation policyNo minimum and no long-term contract; billed monthly
StorageQuotas you set by Class of Service, on disks you provide15 GB included per mailbox; extra in 5 GB blocks at $0.60 a month
Servers and upgradesYou run them; 8 GB RAM production minimum; BSPs must stay on the latest supported versionNo mail server to run; outgoing mail through Amazon SES on shared infrastructure
WHMCS moduleThird-party ModulesGarden module, $15.95 a month or $129.95 a year, WHMCS 8.10 to 9.0Atriomail module 3.1.1 from the Plugins page, WHMCS 9 only
DNS setupDKIM key generated per domain on the server; records added at the DNS hostAutomatic on Cloudflare and Namecheap; records to copy elsewhere; SES records always copied
Calendars and contactsPart of the suite, with ActiveSync and the Outlook Connector as network featuresMail only: webmail, IMAP, POP3 and SMTP, with no calendar or contact sync
BrandingThe servers and their hostnames are yoursPaid add-on: panel on your hostname with your product name and favicon; some layers stay neutral, including webmail and headers
SupportStandard at Authorized, Premier from Silver; you must support clients by email and phoneBusiness hours, by email, phone and in-panel live chat

Where a Zimbra cell depends on your own servers or a private price book, it says so rather than guessing.

Moving 50 or more client mailboxes off a Zimbra server? Talk to us before you quote it. Migration signs in with each account's own IMAP password and moves mail and folders, not calendars or contacts, so the order and the passwords are worth planning first.

Create your account   Talk to the team

When Zimbra Makes Sense

  • Clients who need shared calendars and contacts, not just mailboxes. Zimbra is a collaboration suite with ActiveSync and Outlook Connector sync; Atriomail sells mailboxes.
  • Contracts that require mail on servers you or the client control. Self-hosted Zimbra or Carbonio lets you choose the hardware and its country, a real data residency answer.
  • MSPs already at BSP scale with a Linux team. From Silver up, partners get Premier support and priority lead referrals.
  • A single client buying its own server. XMission, a Zimbra reseller, lists 25 Professional Edition mailboxes at $963 a year with Standard support (XMission's Zimbra licensing page, last edited April 2025, checked September 2026).

Where Atriomail Fits

Take a 200-mailbox client book priced at $5.00 per mailbox, so $1,000 a month in revenue on both paths.

On Atriomail, you pay 200 times $1.39, which is $278 a month, and keep $722 a month above wholesale, about 72 percent. That is before card fees, support time and any white-label fee. Branding is not in the $1.39: if you want clients to see your product name on the control panel, white-label is a separate paid add-on with a one-time setup fee and a monthly fee.

On the Zimbra BSP path, the same $1,000 first covers license rental of at least $300 a month at the Authorized level, at rates Zimbra shares only with approved partners. Then come servers that meet the production minimum, backups, the WHMCS module at $15.95 a month if you use it, and the administration hours you priced earlier. The license rate is private, so run that subtraction with your aggregator's quote.

Choose Zimbra when your clients need calendars and collaboration, or their contracts demand servers you control, and you have the Linux team to run it. Choose Atriomail when your clients mostly need mailboxes on their own domain, you bill through WHMCS 9 or your own portal, and you would rather not commit to a monthly minimum or a mail server. For books that span many client domains, the guide to managing email for many client domains from one account shows the day-to-day side, and the Atriomail pricing page lets you check the per-mailbox and storage figures against your own resale price.

Creating an Atriomail account is free and needs no card, and mailboxes are billed from the first one. Create your account, add one client domain, and look at its DNS Setup dialog before you write the quote.

Run the 200-mailbox numbers with your own resale price. Atriomail charges $1.39 per mailbox with 15 GB included and $0.60 per extra 5 GB block, so your margin is the spread you choose to hold, before card fees, support time and any white-label fee.

Work out your margin   Read the setup guide

Frequently Asked Questions

Is Zimbra still open source?

The source code is still released, but Zimbra has not published free official binaries since version 9, according to its own open-source FAQ. The free options are community-compiled packages or Carbonio Community Edition, and either way you run and patch the servers.

What is the minimum commitment to become a Zimbra BSP?

Zimbra's BSP Program Guide sets the Authorized level at $300 (or €225) a month, through an authorized aggregator, on a calendar-year term with a 90-day cancellation policy.

Can Atriomail migrate my clients off a Zimbra server?

Atriomail's built-in IMAP migration, which has no charge, copies mail and folders from any server that allows IMAP sign-in with a password. It does not move calendars or contacts. Bulk jobs need every account's own password, and large books should be planned with us first.

Can I bill Atriomail mailboxes from WHMCS?

Yes, with the Atriomail module for WHMCS 9, downloaded from the Plugins page in the panel. It supports Create, Suspend, Unsuspend, Terminate and Change Package, and mailboxes or storage that clients add in the WHMCS client area become recurring charges at your prices. Changes made in the Atriomail panel or through the API do not sync into WHMCS billing.

What does the Atriomail white-label add-on cover?

It is a paid add-on with a one-time setup fee and a monthly fee. Once our team has set up your hostname, which needs DNS you control, the control panel on it shows your product name and favicon, and the help center pages show your logo. Some layers stay neutral or show the platform, including raw message headers, the webmail interior, payment pages, system emails and some platform legal documents. We tell you exactly which before you launch.

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