Last updated: 21 July 2026
"Mailbox full" is one of the most common recurring tickets in any M365 estate. Here's how MSPs turn it from repeat unbilled labour into a project fee or a recurring line item clients already expect to pay for.
Two billing models
A scoped cleanup engagement, priced by mailbox count or total data volume — a clean fit for a client who's hit a storage crisis or is heading into a tenant migration and needs mailboxes shrunk first.
"Mailbox health & storage management" billed monthly per seat alongside patching and backup — earns more over the life of the client relationship, and converts a recurring support ticket into a standing, expected charge.
The case for packaging it
If storage tickets are handled ad hoc under a flat support retainer, that's unbilled, repeat manual work every time a mailbox fills up again — the ticket doesn't go away just because it isn't itemised.
Anchor a project fee to what the client would otherwise pay Microsoft for additional storage, or what a slower, more expensive tenant migration would cost with bloated mailboxes — a documented saving is easier to justify than a flat hourly rate.
Running cleanup by hand, mailbox by mailbox, caps how many clients an MSP can service profitably. Deploying self-serve tooling — the MSP bills for setup, licensing pass-through, and oversight, not per-mailbox labour — lets headcount grow on the client side without technician time growing to match.
Two common models: a one-off project fee for a single cleanup engagement (scoped by mailbox count or total data volume), or folding it into an existing managed-service retainer as a recurring line item — e.g. "mailbox health & storage management" billed monthly per seat alongside patching and backup. The recurring model earns more over the client relationship and turns a reactive support ticket into a standing service the client already expects to pay for.
As a line item. "Mailbox full" is one of the most common recurring helpdesk tickets in any M365 estate — if it's being handled ad hoc under a support retainer, the MSP is doing unbilled, repeat manual work every time it recurs. Packaging it as a proactive, scheduled service (or client self-serve tooling the MSP configures once) converts recurring unbilled labour into either a one-off project fee or predictable recurring revenue.
Pricing varies by market, but the anchor most MSPs use is the client's own avoided cost: what they'd otherwise pay Microsoft for additional storage, or what an in-place tenant migration would cost if mailboxes stayed bloated (see how mailbox size drives migration cost). A project fee positioned against a documented storage-cost or migration-cost saving is easier to justify than a flat hourly rate.
Both models exist. An MSP can run cleanup directly with admin access to a client's tenant, or deploy self-serve tooling (like MailBroom for Business, which signs in via Microsoft SSO and gives every employee on the domain their own cleanup access) and bill for the setup, licensing pass-through, and ongoing oversight rather than per-mailbox labour. Self-serve tooling scales to larger client headcounts without the MSP's own technician time scaling alongside it.
Yes, but it's set up per client tenant, not once across an MSP's whole book of clients. MailBroom for Business is licensed per organisation — an MSP would configure Microsoft SSO sign-in separately for each client tenant it wants to offer the service to, which also means it can be introduced client by client rather than requiring a single all-or-nothing rollout.
Deploy MailBroom for Business under a client's own tenant, then bill for the setup and oversight — not the per-mailbox labour.