Give Each Client Their Own Storage Limit

When you resell email, every client draws on your account's storage. One busy client can use up space another was counting on, and each client's admin sees your account's total as if it were theirs.

A storage limit gives a client's domains one amount of space, for example 50 GB. Email and Drive in those domains count toward it, and the client's admins split it between their mailboxes, the same way you split your account.

Why set a limit

• A size you can sell. Mailbox sizes the client hands out never add up to more than the limit.
• Less work for you. Their admins manage mailbox sizes themselves. When they need more space, the dashboard asks them to contact their administrator, without naming your company.
• Your total stays private. Their overview shows their limit, not your account.
• One number for several domains. One limit covers all of a client's domains.

Set a limit

The account owner can change limits, and so can a team member who manages people and reaches every domain. Someone limited to some domains, such as a client's own admin, never sees this setting.

1. Open Team & clients.
2. Choose Edit access on the client's row, or Invite people for someone new.
3. Choose their domains. A Storage section appears once the person is limited to at least one domain.
4. Choose Own limit, then type a size in GB or pick 10, 25, 50 or 100 GB.
5. Save.

The limit covers every domain on the person's list. Anyone else holding one of those domains appears under Also applies to, because they share the limit.

A bar shows what the domains already hold. A limit can't go below the fixed sizes and pending invitations in those domains, or below what they already store. The dialog explains which under the field, and quick sizes below it are greyed out.

Nothing about storage is saved unless you choose it: click a card, type a size or pick a quick size. Editing someone's role or permissions later leaves their limit alone.

If the domains you pick are partly under a limit and partly not, neither card is selected and a notice says so. Choose Own limit to put them all under that limit, or Account storage to take the limit off.

When you untick a domain that is under a limit, the dialog says what saving will do: the domain leaves the limit, or it stays because someone else still has it.

To remove a limit, choose Account storage and save. The dialog first lists the domains and people affected. Mailboxes keep their fixed sizes, and mailboxes on shared storage use your account's free space again.

The Team & clients list shows a Storage column: usage against the limit, such as "3.4 GB of 50 GB", Account storage when there is no limit, or By domain when someone's domains are under different settings. Storage changes you make here appear in the Team timeline.

A limit whose domains nobody on your team has, such as one set through the API before you invited the client or one kept after you removed them, appears below the list under Storage limits without a client, where you can change its size or remove it.

What the client's admin sees

When all of a person's domains share one limit, and that limit covers no other domain:

• Overview. The Storage card is labelled Your storage limit and measures email and Drive in their domains against it. It shows Filling up at 75% and Almost full at 90%, and suggests freeing up space or asking their administrator for more.
• Mailbox sizes. In Edit storage, and when they create a mailbox or invite someone, the available space shown is what the limit still has free, never more than your account has left.
• Too big. A size that doesn't fit shows "This is more than your storage limit allows. To get more space, ask your administrator."
• Drive. The Client role no longer includes Account Drive, so Drive is not in their dashboard menu. Each mailbox keeps its own Drive in webmail.

If a person's domains are under different limits, some have none, or their limit also covers a domain they don't have, their overview shows the account's storage as before. Keep each client's domains in one limit, and give their admins all of those domains.

When you, or anyone else who can change limits, pick a size that doesn't fit, the message says how much the limit has left and that you can raise it in Team & clients.

Emails as a limit fills up

When a limit reaches 75%, 90% and 100%, the client's people who manage mailboxes get an email. At 90% and 100%, you get one too. The first two are the same points where their overview shows Filling up and Almost full.

Who gets it on the client's side. People on the client's side, limited to that client's domains, who have every domain under the limit and can manage mailboxes: the Client and Mailbox Operator roles, and a Custom role that can manage mailboxes. People with Domain Administrator, Read-only or Webmail only, people who haven't accepted their invitation yet, and people whose access is suspended don't get it. People on your own team who reach every domain get the email to you instead, if they can change limits.

What it says. The subject is "Your storage is 75% full", "Your storage is almost full" or "Your storage is full". The email:

• says how much is used, for example "38 GB of 50 GB", and which domains share the space;
• lists up to three mailboxes using the most space, with their sizes;
• at 90%, warns that some mailboxes will stop receiving new email when the space runs out, and at 100%, that some may not receive new email until space is freed;
• explains how to free up space: delete old messages and large attachments, empty the Trash, and remove Drive files they no longer need;
• tells them to ask their administrator if they need more space, without naming your company;
• has an Open mailboxes button that opens Mailboxes in their dashboard.

Whose brand it carries. The email looks like the dashboard it leads to. When the client's domain has an active branded Dashboard address, the email shows your brand name, logo and colours, comes from your Sender address if you set one, and replies go to your Reply-to address. The button opens your branded dashboard. Without a brand on the domain, it is a plain TrekMail email, like their dashboard. Each person gets it in their own language, or in the account owner's language if they haven't chosen one.

The email to you. The account owner, and anyone on your team who can change limits, gets an email at 90% and 100%. It is a TrekMail email, like the rest of your account mail. The subject is "A client's storage is almost full" or "A client's storage is full", followed by the client's domain. It names the limit's domains, shows how full it is, for example "47 GB of 50 GB", and says which of the client's people were told. The Open Team & clients button takes you to where you can raise the limit.

How often.

• One email each time usage passes 75%, 90% or 100%. There are no weekly reminders.
• If usage passes more than one of these points between checks, only one email goes out, about the highest.
• The same email comes again only after usage drops at least 5 points below that point and then climbs back. For example, after the 90% email the client frees space down to 80%; if usage reaches 90% again later, they get a new email.
• Usage is checked a few times a day, after mail usage is recounted. Mail usage can lag by a few hours, so an email can arrive a few hours after usage gets there.
• These emails can't be unsubscribed from.

Shared storage and fixed sizes inside a limit

Mailboxes inside a limit work the way they do in your account, one level down:

• Fixed size. A mailbox with its own size reserves it from the limit, for its mail and its Drive files. Fixed sizes and pending invitations never add up to more than the limit.
• Shared storage. A mailbox with Shared storage ticked uses the limit's free space: the limit minus the fixed sizes, never more than your account has left.

Two rules are stricter here. A mailbox can't be made smaller than what it already holds; making it bigger is fine whenever the limit has room. And a fixed size that doesn't fit the limit is refused for everyone, you included.

Each mailbox on shared storage is capped on its own at the limit's free space, as in your account. If several of them grow at once, their total can pass the limit, and the Storage column shows it. For a hard ceiling on one mailbox, give it a fixed size. Mail usage is recounted every few hours, so the figures can lag behind.

Drive inside a limit

Drive files of mailboxes in a limited domain count toward the limit. Those mailboxes also:

• don't see the folders you share with all mailboxes, which may hold other clients' files;
• can't share their own folders with all mailboxes;
• can't upload from sync apps (WebDAV) once their space is full. Deleting still works, so a full client can free space from the app.

Your own Account Drive counts toward your account, not toward any client's limit.

API and MCP

You can also read and set client storage limits, and change a mailbox's size, through the REST API and the MCP server. The same rule applies: only a caller that manages people and reaches every domain can change a limit. See Manage White Label teams with API and MCP and the REST API overview.

REST endpoints, under /api/v1. Sizes are in MB, and every write takes an Idempotency-Key header:

• GET /white-label/client-limits and GET /white-label/client-limits/{id}: list the limits or read one, with what is reserved, shared and used (members:read).
• POST /white-label/client-limits: give domain_ids a limit of storage_limit_mb, or change the one they already share (members:write).
• PATCH /white-label/client-limits/{id}: change the size, the full domain set, or both (members:write).
• DELETE /white-label/client-limits/{id}: remove a limit; its domains go back to your account's storage (members:write).
• PATCH /mailboxes/{id}/storage: set storage_allocation_mb to a fixed size, or to null for shared storage (mailboxes:write).

MCP tools: list_client_limits, set_client_limit and remove_client_limit in the White Label toolset, and set_mailbox_storage. On a self-hosted server, the three that change something need TREKMAIL_ALLOW_DESTRUCTIVE=true, and remove_client_limit also needs confirm_remove=true.

Errors to expect:

• client_storage_limit_exceeded (422): a fixed size doesn't fit what the limit has left; details.available_mb says how much does.
• client_storage_below_usage (422): the mailbox would be smaller than what it already stores; see details.used_mb.
• client_storage_limit_too_low (422): the limit would be lower than what its domains reserve or store; see details.minimum_mb.
• client_storage_domains_conflict (409): the domains are under different limits.

Common questions

How do I move a domain from one client to another? Take it off the first client's list and save. The dialog tells you whether the domain leaves their limit or stays under it because someone else still has it. Then add it to the second client. If that client has a limit, choose Own limit and save to put the domain under it; otherwise just save. Keep that order, because domains under two different limits can't be given one.

Can I lower a limit? Yes, down to the fixed sizes and pending invitations in its domains, or what they already store, whichever is higher. To go lower, the client first deletes mail or files, or moves mailboxes from a fixed size to shared storage.

What happens when the limit is full? A mailbox on shared storage stops accepting mail once it holds all of the limit's free space, and a mailbox with a fixed size once it is full. Senders get a bounce, and Drive uploads are refused. Reading, downloading and deleting keep working. Emails warn the client's people who manage mailboxes at 75%, 90% and 100%, and you at 90% and 100%, as described above.

What about domains the client adds? They join the client's domain list and the limit their domains share.

Do I need White Label Lite? The limit applies as soon as you save it. Your clients can sign in to your dashboard once White Label Lite is active.

Can my clients' limits add up to more than my account has? Yes. A limit is a ceiling, not a reservation, and no client gets more than your account has left.

Related

• Team roles and what each one can reach
• Change a mailbox's storage size
• Mailbox storage and pooled quotas explained