Outlook for supply chain planners on Mac: setup, rules and shared mail for 2026

Which Outlook for Mac you use in 2026

Start with the version. Microsoft's release notes list New Outlook for Mac build 16.114 from October 14, 2026 as the newest build in the notes. Open the app and compare your build with that number before you follow any menu path in this guide.

The older client is called Legacy Outlook. Microsoft says it stops working with Exchange Online in October 2026. A university IT post gives October 1, 2026, for users who turned on the Legacy Outlook switch. Both dates are now in the past.

If you still open the old client, talk to IT this week. Do not wait for an update to fix it for you. Your admin knows which date applies to your account.

To switch, open Outlook and turn off the Legacy Outlook switch. Microsoft's support page says you can go back with Help > Revert to Legacy Outlook. An AI-generated reply on Microsoft's Q&A site says that toggle moved in newer builds. If you do not see it where Microsoft says, look through the menus in your build.

• Signatures. Copy the text from the old signature first, then rebuild it in the new client. The steps are in the signature guide.
• Saved searches. These become Smart Folders. Open each one and check that it still returns the supplier mail you expect.
• Local folders. Confirm that the folder migration finished before you delete anything in the old client.
• Old archives. Build 16.110 from June 16, 2026 added Import PST, so older .pst files can come across.
• The old profile. Keep it until the new client has shown you a full month of supplier mail.

Add your accounts and shared planning mailbox

New Outlook for Mac works with work or school accounts, Microsoft accounts and third-party accounts. Those include Google, iCloud, Yahoo, POP and IMAP mail. It needs macOS 10.14 Mojave or later. For the add-account steps, read How to add an email account in Outlook on Mac.

Planning teams often share one inbox for a supplier group or a desk. Microsoft lists hybrid shared mailboxes as coming later for New Outlook for Mac. Some GCC environments also show Rules not supported for this account. If your shared mailbox will not appear, ask IT whether it is hybrid before you spend time on it.

Once the mailbox shows up, follow How to add a shared mailbox in Outlook on Mac. Then send a test message from it to yourself. That shows you the sender name, the folder and the reply path in one go.

Attachment size limits for forecast workbooks

Exchange Online sets the message and attachment size for Outlook for Mac at 150 MB. The default maximum message size is 35 MB to send and 36 MB to receive. Admins can set those limits anywhere from 1 MB to 150 MB.

Here is a worked example. Your weekly S&OP workbook is 60 MB because it holds years of history and many chart tabs. The attachment limit reads 150 MB, so you attach it. The message still fails under the default 35 MB send limit. Always check the send limit, not the attachment limit.

New Outlook for Mac uses the lowest of several values from your mobile device mailbox policy. Those values are MaxAttachmentSize, MaxSendSize and MaxRequestSize. So an admin can cut the real limit below 150 MB. Exchange Online Kiosk accounts are capped at 35 MB for attachments.

Shrinking the file usually beats asking for a policy change. Delete old tabs, paste values where formulas are not needed, and remove charts nobody reads. Zipping an .xlsx rarely helps, because the file is already compressed.

• Check the real size in Finder. Select the file and press ⌘I to open Get Info.
• Compare it with the 35 MB default send limit, not the 150 MB ceiling.
• Ask IT which send limit applies to your account, and get the answer in writing.
• For a file over your limit, send a link from your cloud drive instead of the file.
• Name the version in the body, so the supplier knows which file they have.

Recipient limits when you email every supplier

Exchange Online allows up to 1,000 recipients per message by default. Admins can set that number from 1 to 1,000. Each sender is also limited to 10,000 recipients per 24 hours.

Worked example. You need to send a delay notice to a supplier list that is just over 1,000 contacts. Split the list into two messages. Put the suppliers in Bcc, not To, so they cannot see each other's addresses. Send the first batch, then the second.

One trap applies to some tenants. An onmicrosoft.com domain is throttled to 100 external recipients per 24 hours. If your company uses that domain, a supplier blast can stall after the first 100. Ask IT before a big send, not after.

Meeting invites have their own ceiling. Invitations, updates and cancellations cover up to 5,000 recipients per outgoing meeting message. For the invite steps, read How to send a meeting invite in Outlook on Mac.

Rules, Focused Inbox and junk mail for supplier threads

Rules are the first thing planners set up and the first thing that breaks. Microsoft's support page lists known gaps for New Outlook for Mac. A June 16, 2026 thread on Microsoft's Q&A site reports rules not working, search problems and junk-mail reporting failing. Those are user reports, not confirmed bugs.

Build the rule, then test it. Send a message from another account that should match. Check the folder it lands in. Then delete the test message. The full steps are in How to create a rule in Outlook on Mac.

Focused Inbox can hide supplier mail in the Other tab. If a supplier says they sent a confirmation and you cannot find it, check Other first. To turn Focused Inbox off, follow How to turn off Focused Inbox in Outlook on Mac.

• Test each rule with one real supplier message before you trust it.
• Check the rule's target folder, not only the Inbox.
• Use filters for supplier threads, not a broad search. See How to search with filters in Outlook on Mac.
• Open the Junk folder each morning and look for supplier mail, because junk reporting may not work.

Use Outlook as the hand-off layer around Excel

Outlook rarely plans anything. It moves the plan around. An ABC Supply Chain survey published in November 2025 found that 81.1% of 164 S&OP and IBP professionals use Excel or Google Sheets to manage the process. Dedicated software came in at 5.1%, and ERP systems at 6.6%. The survey was run by a vendor, so treat the numbers as directional.

A retail supply chain analyst told the same article, "Each team has their own spreadsheet." That is the inbox problem in one line. Several versions of one forecast can sit in several sent folders at once.

The 2024 LeanDNA and Wakefield Research survey asked 250 supply chain, inventory and planning executives. About 14 hours per week went to manually tracking data, almost two workdays. The press release does not say what share of the week that is, so do not turn it into a percentage.

Name files so the newest one is obvious. A pattern that works is forecast_weekly_v3_2026-11-09.xlsx, with the version in the subject line too. Reply on the same thread, so the history stays in one place.

• Use one thread for each topic, such as one supplier or one lane.
• Put the file version and the cut-off date in the subject.
• Reply all only when every person on the thread needs the answer.
• Move closed threads into a folder. See How to create a folder in Outlook on Mac.

Templates for weekly supplier and planning emails

Built-in templates need a Microsoft 365 subscription and Outlook for Mac 15.35 (build 170610) or later. Microsoft's article describes File > Save As Template to save one, and File > New > Mail From Template to reuse it. That article covers the classic client, so check whether the menu matches in New Outlook before you rely on it.

The My Templates add-in is a different tool. It needs a Microsoft Exchange account. It is not available in shared mailboxes opened in Outlook for Mac, and an admin can hide it. If your planning mailbox is shared, plan on the built-in method.

Start with the emails you send every week. Keep each template short. Put the open questions at the top, where the supplier reads first, not at the bottom where they may never scroll.

• Supplier delay notice: part, original date, new date, and the one thing you need from them.
• Weekly S&OP update: forecast version, the changes since last week, and the open risks.
• PO confirmation request: PO number, quantity, and the ship date you need.

Need one-click actions too? How to create a Quick Step in Outlook on Mac covers the options.

Catch mistakes before they leave the Outbox

Outlook for Mac build 16.111 from July 14, 2026 lets you edit a message in the Outbox before it sends. Use that window to fix the wrong attachment, the old file version or a misspelled supplier name.

Schedule send gives you a planned delay. Undo Send gives you a short window to take back a message you just sent. Both are covered in How to delay delivery of an email in Outlook on Mac. Use Schedule send for a forecast that should land when the supplier opens their inbox, not the moment you finish writing it.

Before any planning email goes out, check the attachment name, the version in the subject and the recipient list. Most bad sends fail on one of those three checks.

Where Lazur fits into Outlook on your Mac

Lazur is a voice assistant that lives in the notch on your Mac. Hold ⌥ ⌘ to ask about anything on screen, and Lazur answers out loud. Hold fn to dictate clean text at the cursor in any app. Lazur is not a plugin or add-in for Outlook or any other app.

Lazur does not click buttons or run Outlook for you. It points and guides. Ask where something is, and Lazur draws a circle and a label around it on your screen. Ask how to do something, and Lazur guides you one click at a time, waiting for each click.

Here is a typical moment. You are in a supplier thread, and you cannot find the filter for unread replies. You hold ⌥ ⌘ and ask. Lazur circles the control and says what it does. You click it, then ask the next question.

• Where is the filter for unread supplier mail?
• Walk me through attaching a file from my desktop, one click at a time.
• Read this thread out loud and list what the supplier wants from us.
• Draft a delay notice from these bullet points.
• Hold fn and dictate the weekly update into the message body.

Privacy is simple to explain. Lazur listens and looks at the screen only while you hold the shortcut. Audio and the screenshot go to AI providers to produce an answer, and they are not stored. Content is never used to train AI models.

When the plan in Excel and the email disagree

Here is a common case. A supplier email moves a ship date by a week, but your forecast tab still shows the old date. Two sources now disagree, and the wrong one will get used in the next meeting.

Fix it in this order. Reply on the supplier thread with the new date and ask them to confirm it. Update the workbook, then save it as a new version rather than overwriting the old one. Send a one-line note that links the new version to the thread.

Keep the old version in a folder for a few weeks. If someone asks why a number changed, you can show both files and the thread that explains it.

First-week setup checklist for planners

1. Check your Outlook build, and turn off Legacy Outlook if it is still on.
2. Add each account again, including the shared planning mailbox.
3. Confirm that signatures, saved searches and folders came across.
4. Send a test file near your limit, then check whether it arrives.
5. Create one rule and test it on a real message.
6. Build templates for the emails you send every week.
7. Ask IT for your send limit and recipient limit, in writing.

Where to go next

If you want the short version, start with the Outlook page for supply chain planners and the setup steps above. You can get Lazur from the download page. The pricing page lists the trial and the plans.