What happens to the signature when a mailbox becomes a shared mailbox?

Without centralised management, it stays as it is: messages sent from the shared mailbox keep being signed in the name of the person who left. With centralised management, removing the link deletes the named signature.

Should a leaver's mailbox be deleted immediately?

Rarely: correspondents keep writing to the old address for months. Common practice is to keep the mailbox on restricted access with an auto-reply, for a period set by your retention policy.

What should the auto-reply contain?

That the person has left the company, the name and address of a genuinely reachable successor, and nothing else. Avoid generic addresses nobody monitors and wording that suggests a temporary absence.

How long should the mailbox be kept?

The duration falls under your retention policy and any sector-specific obligations. It should be written down and applied uniformly, rather than decided case by case.

When an employee leaves: removing their signature and securing the mailbox

What to do with the signature, the mailbox and the auto-reply when an employee leaves — and why a signature left in place is as much an image problem as a security one.

An employee’s departure is handled seriously for accesses, licences and equipment. The signature, though, almost always stays in place — and keeps travelling to customers for months.

The most common symptom: a shared mailbox signed in an absent person’s name

The scenario is banal. A salesperson leaves the company. Their mailbox is converted to a shared mailbox so the team can keep handling their live accounts. Three colleagues access it and reply to customers.

Every reply goes out with the departed person’s signature: their name, their job title, their work mobile number. The customer believes they are writing to them, is surprised by the different tone, and sometimes calls a number that no longer answers.

It is an immediate image problem, and sometimes a compliance one: you are distributing the professional contact details of someone who no longer belongs to the organisation.

The three things to handle, in order

1. The signature. It has to stop being named as soon as the person leaves. If the mailbox becomes shared, it should carry a departmental signature — “Sales team — Company” — rather than an individual’s.

2. The auto-reply. It informs correspondents and redirects them. It is the most visible element and the most often botched.

3. The mailbox itself. Retention, restricted access, then deletion according to your policy.

What the auto-reply should contain

Three pieces of information, no more:

the person has left the company (in the past tense, with no ambiguity against a temporary absence);
the name and address of a genuinely reachable successor;
optionally, the date from which the address will no longer be monitored.

Two mistakes to avoid. Pointing at a generic address nobody monitors: the message disappears. And writing a vague formula — “is no longer handling this account” — which leaves the correspondent with nobody to talk to.

Worth knowing: check the auto-reply does not stack with the old named signature. A message announcing someone’s departure, signed by that same person, produces a particularly unfortunate effect.

Why this fails under manual management

Removing the signature assumes somebody thinks of it, at a moment when attention is on accesses and equipment. There is no alert, no blocker, no immediate consequence: nothing flags the omission.

And if the signature was configured locally by the employee themselves, you have to access their mailbox to remove it — an operation nobody wants to do on a Friday evening.

The result: in most organisations, you find shared mailboxes signed for years in the name of people who left.

What centralised management changes

When the signature is applied by the service from the directory link, removal becomes an automatic consequence of the departure.

The account is disabled or moved out of the linked unit: the named signature stops being inserted. If the mailbox becomes shared, it is attached to a “functional mailboxes” unit carrying a departmental template.

No specific action is asked of the IT team, and the omission is no longer possible — the mechanism is the same as for arrival, described in preparing a new employee’s signature.

Writing the subject into the offboarding procedure

Technical automation does not dispense with a line in the HR checklist. Three points are enough:

Move the account out of the named organisational unit.
Enable the auto-reply, with the successor’s name.
Set the mailbox deletion date according to the retention policy.

Those three actions take two minutes and sit in the same place as returning the equipment.

The link with brand governance

A signature left in place after a departure is the symptom of a wider problem: nobody owns this asset. It is the same mechanism that lets old logos and expired legal notices circulate — a subject covered in brand governance.

The right question to ask internally is not “who removes a leaver’s signature”, but “who is responsible for what goes out of our mailboxes”. The full framework is in the guide to company email signature management.