Email isn't sending, or a message never arrived
Work out first whether the problem is your Outlook, the recipient's mail server, or a filter holding the message. The bounce wording and a quick check in Outlook on the web tell us which.
Step-by-step troubleshooting
- 1
Check Outlook on the web
Go to outlook.office.com and look for the message there. If it sent or arrived fine on the web, the fault is the Outlook app on your computer, not your mailbox.
- 2
Look in the Outbox and Drafts
A message sitting in the Outbox usually means a huge attachment or a lost connection. Open it, remove attachments over about 20 MB, and send a link from SharePoint or OneDrive instead.
- 3
Read the bounce message
Copy the whole bounce, including the code. 550 usually means the address doesn't exist or you've been blocked at their end; 552 or quota means their mailbox is full; anything about a policy means a filter stopped it. Send us the full text, not a summary.
- 4
Check Junk and quarantine
Look in Junk Email and Deleted Items, and search for the sender's domain. Legitimate mail can also be held in our email protection quarantine — log a ticket with the sender's address and the approximate time and we'll release it and whitelist them.
- 5
Check the rules
In Outlook go to File then Manage Rules & Alerts (or Settings then Rules on the web). An old rule filing or deleting mail is a common cause of 'missing' messages. Also check you don't have a forward set that you've forgotten.
- 6
Check your mailbox size
If you're near your storage limit, sending stops. Empty Deleted Items and Junk, then log a ticket — we can archive older mail properly rather than you deleting things you may need.
Contact us straight away if…
- Nobody in the business can send or receive — call us, that's an outage.
- You're getting bounces saying your domain is blacklisted, or contacts report spam from your address.
- Mail stopped right after a website or DNS change.
Include this in your ticket
- The full bounce message text
- The sender or recipient address and the time of the message
- Whether it also fails at outlook.office.com
- Whether it affects one person or everyone
Still stuck? We'll take it from here
Log a ticket with what you already tried and our Australian help desk will pick it up. Anything urgent, phone 1300 904 635.
Related guides
Websites & DNS
Change DNS for a website or move to a new host
Plan 3 business days
Cyber security
You received a phishing or scam email
5 minutes