Outlook for Finance Teams: Rules, Calendar Sharing, Delegation and Shared Mailboxes

Finance teams rely on Outlook for more than email: rules to sort incoming messages, shared calendars for close dates and leave cover, delegates for managers, and shared mailboxes for queries such as accounts payable or payroll. Microsoft documents each of these features, and they differ in who can use them and what permissions they need. This post summarises Microsoft's support and Exchange Online pages, and adds practical tips that are clearly labelled as ours. Menus, names and availability vary by version and licence, so check the current Microsoft documentation, and ask your IT administrator where a setting needs admin rights. If you are also weighing up AI assistance inside Outlook, Word and Excel, our overview of Microsoft Copilot for finance teams is a good starting point.

Rules: automating the inbox

Microsoft's article on managing email with rules says that rules automatically perform specific actions on email that arrives in your inbox, such as changing a message's importance, moving it to another folder or deleting it. For new Outlook for Windows, it describes a quick route: right-click a message, hover over Rules, select Create rule, choose a destination folder and select OK, which moves future mail from that sender to the folder. For a full rule, More options opens the settings. Every rule needs a name, at least one condition and at least one action; exceptions are optional.

The same article describes how rules are managed:

• Rules apply in the order they appear in the list, and you can reorder them with the arrows.
• A "Stop processing more rules" checkbox stops later rules from running on a message that matches.
• Rules apply to incoming mail by default; a "Run rule now" option applies a rule to messages already in your mailbox.
• A toggle pauses a rule without deleting it.

It also lists caveats. New Outlook does not support rules for third-party accounts such as Gmail, Yahoo and iCloud, which you configure through the email provider. Some rules created in classic Outlook are client-side and cannot run in new Outlook, so the page says to create a replacement rule. The article applies to Outlook for Microsoft 365, Outlook 2024, 2021, 2019 and 2016, Outlook.com, new Outlook for Windows and Outlook Web App, but the steps we describe cover new Outlook for Windows only. Its metadata shows a published date of 05/07/2026 and an update date of 2026-08-05.

Our suggestion: use rules to sort and flag, not to hide. For example, you might route supplier statements to a folder and colour them, but avoid rules that delete mail automatically. Review your rule list when your role changes, because the order of rules matters and old rules can quietly move mail you need. Also be cautious about rules that forward mail outside your organisation, and check your organisation's policy first.

Calendar sharing: view, edit and delegate

Microsoft's article on sharing a calendar with edit or delegate permissions names the following permission levels:

• Editor (labelled "Can edit"): can view and change the calendar.
• Delegate: has editor rights plus can schedule and respond to meetings on the owner's behalf.
• View-only levels: "Can view when I'm busy", "Can view titles and locations" and "Can view all details", which are the options available to people outside your organisation, who cannot be given editor or delegate access.

According to the article, editors can be assigned to the primary calendar or to additional calendars you created, but delegates can only be assigned to the primary calendar. Access for editors and delegates is limited to people in your organisation, and delegate access requires a work or school account in Microsoft 365 or Exchange Online. In new Outlook you select Calendar, then Home, then Share Calendar, enter a name or email address, choose the access level and select Share. Recipients receive an email invitation and select Accept to add your calendar to their list.

For delegates, the article also has you set how meeting requests and responses are routed: "Delegate only", "Delegate and send me a copy" or "Both my delegate and me". On private items, it says items marked Private show only the time to most people you share with, while a "Let delegate view private events" checkbox lets a delegate see the details. When you stop sharing, internal users lose the calendar from their list, whereas external users keep their copy but it no longer syncs. The article applies to Outlook for Microsoft 365, 2024, 2021 and new Outlook for Windows, with a metadata date of 03/09/2026 and update timestamp of 2026-09-18.

Our suggestion: give the minimum level that does the job. A finance close calendar might be shared as view-only with the wider team and editable only by the controller's office. Treat delegate access as a significant permission and review it periodically.

Shared mailbox, shared folder, shared calendar, delegate: the differences

Microsoft's article "About shared mailboxes, shared folders, and shared calendars in Outlook" sets out the differences. A shared mailbox gives group or individual access to an entire mailbox, including folders, calendars and contacts, and replies appear to come from the shared address. It requires a work or school account and admin setup. A shared folder lets you share chosen folders in your mailbox with people in your organisation; "Send as" rights need IT admin setup. A shared calendar covers only your calendar folder and works with work, school and personal accounts, usually without admin setup. A delegate is a person granted permission to manage your mailbox, who can send or respond to mail and calendar items on your behalf. The page has a metadata date of 01/12/2026 and an update timestamp of 2026-09-18.

Shared mailboxes in Exchange Online

Microsoft's Exchange Online documentation describes a shared mailbox as a way for a group to monitor and send email from a common account, such as an info or support address. When a group member replies, the message appears to come from the shared mailbox rather than the individual. The page documents three permissions:

• Full Access: lets a user open the mailbox and act as its owner, including creating calendar items and reading, deleting and changing email. Users cannot send email from the mailbox unless they also have Send As or Send on Behalf.
• Send As: lets a user send mail that appears to come from the shared mailbox.
• Send on Behalf: lets a user send mail that shows as "[User] on behalf of [Shared mailbox]". The page says the admin center cannot grant it, and gives a PowerShell route for administrators.

The page also says that both Full Access and Send As are required for successful shared mailbox operation, although its Full Access description says Send As or Send on Behalf is enough to send, so confirm which permissions you need with your IT administrator. It also contains two notes worth passing to your IT team. First, creating a shared mailbox in Exchange Online also creates an active user account with a system-generated (unknown) password, and the page links to guidance on blocking sign-in for that account. Second, when users move items between folders in a shared mailbox, a copy is stored in the Recoverable Items folder. The page documents no mailbox size limits and no licensing statements, and we say nothing about either. The page shows an ms.date of 2018-06-26, a footer showing last update 2024-03-07 and a later metadata timestamp of 2026-08-03, so check the current version.

Our suggestion: for a team address such as payables or payroll queries, agree who is responsible for monitoring the mailbox each day, how to mark a message as being dealt with, and who may send from it. Document those rules so that cover during leave is clear.

Permissions, records and AI tools

Our view: shared mailboxes, shared folders and delegate access widen who can see business email, so it is worth considering the implications for retention and data protection. We do not state any retention periods here. For HR records, see our guide to employment records retention periods in Ireland and check what applies to the records in your mailbox. If your organisation uses Microsoft 365 Copilot, access permissions also matter for what the tool can surface; our guide to Microsoft 365 Copilot data governance and permissions covers that.

A short checklist: our suggestions

• List every shared mailbox, who has Full Access, Send As and Send on Behalf, and review the list when people change roles.
• Share calendars at the lowest level that works, and record who your delegates are.
• Review rules after any change of role or after migrating to new Outlook, because classic client-side rules may not carry over.
• Keep a short written procedure for each shared mailbox covering ownership, response times and escalation.

Learnsignal's offices are off Baggot Street in Dublin, and we offer in-person training from there. For current details, see our CPD pages.

Frequently asked questions

What is the difference between Editor and Delegate access on a calendar?

Microsoft says an Editor can view and change the calendar, while a Delegate has editor rights plus can schedule and respond to meetings on the owner's behalf. Delegates can only be assigned to the primary calendar.

Does a shared mailbox let me send as the shared address?

Not by Full Access alone. Microsoft says Full Access users cannot send email from the mailbox unless they also have Send As or Send on Behalf.

Why has my Outlook rule stopped working in new Outlook?

Microsoft says some rules created in classic Outlook are client-side and cannot run in new Outlook, and that new Outlook does not support rules for third-party accounts such as Gmail. Create a replacement rule or configure the rule with your email provider.

Can external people see my calendar?

Microsoft lists view-only levels for people outside the organisation, but says editor and delegate access is limited to people in your organisation. When you stop sharing with an external user, they keep their copy but it no longer syncs.

Review your rules, calendar shares and shared mailbox permissions regularly; each is easy to set up and easy to forget.