The operating principle
Mailbox ownership, sending rights and data retention are separate
Granting a colleague access to read a mailbox does not automatically answer who may send as it, preserve its records, manage the group or delete it. Each decision needs a named approver and a periodic review.
Choose the recipient object deliberately
Inventory user mailboxes, shared mailboxes, room and equipment resources, distribution lists and mail-enabled groups. For each entry record its business owner, delegates, aliases, external senders and retention expectations. Microsoft distinguishes recipient types in its Exchange documentation because their permission and lifecycle behaviour differs.
Test common scenarios rather than assuming every mailbox should become shared. A team might need messages delivered to several personal inboxes, a collaborative address with a shared history, or an automated application sender. These are different requirements. Avoid creating expensive user identities or permanently delegated rights purely to work around an unclear process.
| Workload | Choice to verify | Governance question |
|---|---|---|
| Team's shared conversation | Shared mailbox and delegate rights | Who may read and reply? |
| Distributing notices | Distribution group or Microsoft 365 Group | Who changes membership? |
| External application mail | Approved relay or sending method | Which service owns authentication? |
| Departing staff inbox | Retention or conversion decision | Who approves records and onward access? |
Treat delegated rights as controlled changes
Mail access can be broad and difficult to notice. Record Full Access, Send As and Send on Behalf permissions separately. Microsoft's recipient-permissions guidance explains that Send As and Send on Behalf have distinct effects. Require business approval for financial or customer-facing shared mailboxes, then verify the permission in a test account rather than simply closing an admin ticket.
Maintain an owner review cadence for unattended mailboxes and long-lived delegates. Service accounts and forwarding rules deserve particular attention because they can remain after the original employee changes role. An account that still receives messages is not proof that its access remains appropriate.
Documented administration controls
- Map shared-mailbox, group and delegated permissions
- Separate ownership approval from technical execution
- Review external forwarding and application senders
- Check authentication, accepted domains and routing records
- Record test sends and receives from outside the organisation
Handle problems across mail flow and identity
A blocked or missing message can result from transport rules, DNS authentication, recipient configuration, Microsoft service health, quarantine or an external sender's setup. Diagnose the route and identify which layer is responsible before changing a policy. A hurried global rule change made to rescue one sender can introduce a wider security problem.
Retention requirements are not the same as restoring a missing message. Coordinate with the customer's records owner and security team when an enquiry involves legal hold, deletion or compromised access. Scope these separately when they exceed ordinary mailbox administration. The handover record should explain what was altered, how it was tested and which risks remain.
Separate mail flow, recipient access and records preservation
An Exchange administrator may be asked to solve a missing-message complaint, a new shared mailbox or an executive delegation change. Each touches a different boundary. Trace external delivery through accepted domains, connectors, authentication and message trace; address mailbox access through approved recipient permissions; treat retention, eDiscovery and legal holds as compliance-owned decisions.
Application-generated mail is a recurring failure source. Inventory senders using the corporate domain, including websites, printers, CRM platforms and finance tools. Check authorised mechanisms and SPF, DKIM and DMARC alignment before changing routing; a successful mailbox sign-in does not establish that invoices or password reset emails are being delivered.
| Exchange request | Evidence | Decision owner |
|---|---|---|
| Mail flow outage | Message trace, DNS/authentication and connector rules | Messaging owner |
| Shared mailbox rights | Requested access, delegation type and data sensitivity | Mailbox business owner |
| Retention or hold | Policy purpose, scope and legal basis | Compliance/legal owner |
| SMTP application sender | Approved service identity and sending path | Application and security owner |
Make troubleshooting reproducible
Create runbooks for common incidents but avoid turning them into unsafe one-click fixes. A failed message needs timestamp, sender, recipient, error or trace identifier and whether the failure is inbound, outbound or internal. A permissions issue needs the mailbox and the expected user action. Capture enough evidence to replicate the symptom without transmitting full mailbox exports to a generic web form.
After a change, have the affected user validate Outlook and mobile behaviour, delegated send/reply where relevant and an independent external mail round-trip. Keep logs of elevated access and policy changes. A restored dashboard metric is not evidence that business correspondence works.
Documented administration controls
- Message trace and scope documented before changes
- Delegation approved by mailbox data owner
- Application and third-party senders tested
- Compliance changes separately authorised
- User-visible acceptance recorded after remediation
Exchange administration should leave fewer unowned addresses and clearer decisions. Start by understanding how the organisation uses each recipient rather than charging for the number of mailboxes alone.
Primary technical references
Check current feature and licence requirements before changing a tenant. A service description is not evidence that a customer has purchased or activated an option.
Commercial next step
Review Exchange support and mail-flow ownership
Tell us which Exchange Online objects cause repeat issues, approximate users, required access approvals and operating hours. We can propose a measured administration scope.
Request an administration assessment