Outlook: Can't Send or Receive Email (Microsoft 365)

Category: Microsoft 365 · Audience: Customers & Technicians · Est. time: 10–25 min

Summary

Email that won't send or arrive is usually a connection, a stuck outbox item, or a profile issue. These steps apply to Outlook connected to a Microsoft 365 mailbox.

Symptoms

• New mail isn't arriving
• Messages stuck in the Outbox
• "Disconnected" or "Working Offline" in the status bar

Solution

1. Check you're online. Bottom‑right of Outlook, look for "Working Offline" or "Disconnected." If it says *Working Offline*, click Send/Receive → Work Offline to toggle it back on.
2. Confirm internet + service health. Open a website to confirm internet works. Check portal.office.com or ask BBN if there's a Microsoft 365 service incident.
3. Force a Send/Receive. Press F9 (or Send/Receive → Send/Receive All Folders).
4. Clear a stuck Outbox item. Open the Outbox. A large attachment or a message stuck "sending" blocks everything behind it. Open it, delete or move it to Drafts, then retry. (Tip: switch to Work Offline first so it stops trying to send while you delete it.)
5. Check Outlook on the web. Sign in at outlook.office.com with the same account. If mail flows there, the mailbox is fine and the problem is the Outlook app on this PC.
6. Repair the account. File → Account Settings → Account Settings → (select the account) → Repair.
7. Repair Office. Settings → Apps → Installed apps → Microsoft 365 → Modify → Quick Repair (then Online Repair if needed).

If that doesn't work

• Recreate the mail profile: Control Panel → Mail → Show Profiles → Add, set up the account fresh, make it default.
• Check the mailbox isn't full (Outlook on the web shows a quota warning) — ask BBN to review storage/licence.
• Escalate to BBN Support with: does it work on the web? is it send, receive, or both? any error text?

Prevention

• Keep attachments under ~20 MB; use OneDrive/SharePoint links for large files.