Keeping client inboxes apart inside one agency

An agency ends up holding mailboxes that belong to other people’s brands. The job is to work them all from one place without ever letting one leak into another.

A client's customer is answered from the client's own address, through the client's own server.

The shape of the problem

A small agency with six clients tends to accumulate three kinds of address: its own — hello@agency — a mailbox on each client’s domain that the client created for you, and a handful of aliases that forward from somewhere older. The account manager answers all of them, and the one unforgivable mistake is answering a client from the agency address, or worse, from another client’s.

The second problem is turnover. An account manager who leaves should lose access to four mailboxes in one action, and the new one should gain exactly those four and nothing else. If access is a password in a shared document, neither of those is true.

How to arrange it

1Connect each client mailbox as its own mailbox, using credentials the client created for you. Nobody in the agency ever needs to see that password again after it is entered.
2Name and colour each one for the client, so the list reads as a list of clients rather than of addresses.
3Share each mailbox only with the people on that account. A member sees the mailboxes they were given and nothing else.
4Give the account leads the administrator role so they can connect and remove mailboxes; everyone else stays a member.
5Set a signature per address, in the client’s wording rather than the agency’s.
6Verify any alias that arrives in a client mailbox, so a reply to an old address still leaves from that address.

Every query in Mailbind is scoped to the workspace and checked against the membership of the account asking, per resource. That is tested rather than assumed: each resource has a cross-workspace access test in the test suite.

Why the sender rule matters more here than anywhere

On a personal inbox, answering from the wrong address is embarrassing. On a client mailbox it is a billing conversation: the client’s customer now has your agency’s address, replies to it, and the thread leaves the client’s mailbox entirely. Months later the client cannot find the correspondence in their own archive, and they are right to be annoyed.

Mailbind removes the decision. A reply leaves from the mailbox that received the message, through that mailbox’s own SMTP server at the client’s provider, so the message is indistinguishable from one the client sent themselves — same domain, same SPF and DKIM alignment, same archive.

Handover, holidays and the audit question

None of this requires the client to install anything or change providers. You are a client of their mailbox, exactly as an email program would be, and if the relationship ends you disconnect and Mailbind’s copy is deleted.

Assignment and internal notes, so a conversation can be handed to a colleague with its context attached.
AI summaries, which turn a forty-message thread into something a stand-in can read before a call.
A workspace audit log kept for three months, for the week a client asks who sent what.
Needs-reply triage per mailbox, so no client’s queue quietly grows while another is busy.
Removal in one action when someone leaves the account or the agency.

Common questions

Can a member see only their own clients?

Yes. Mailboxes are shared with named members, and a member sees only the mailboxes they have been given.

Do we need the client's main account password?

No — only credentials for the mailbox itself, which most providers let the client create and revoke independently. An app password is ideal, because revoking it affects nothing else.

What happens when a client leaves?

Disconnect the mailbox. Mailbind's synchronised copy is deleted within thirty days, backups within a further thirty, and the mail itself never left the client's provider.

Is this the Team plan?

Yes, for the shared mailboxes and roles. Team is €14 a month per member on one invoice for the agency.

Keep reading

One workspace, one mailbox per client

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Page updated October 29, 2026