Outlook Not Sending or Receiving Emails? Quick Australian Fixes and Checks

Stuck emails in your Outbox or inbox not updating? Here’s a quick Aussie guide to fix Outlook fast. If you’re in Brisbane and seeing Outlook not sending emails, use this step‑by‑step list before it ruins your day.

Outlook not sending or receiving? Use our quick checklist to fix sync, server and account issues fast. Clear steps for Telstra, Optus, iiNet and Microsoft 365 users.

Key takeaways

• Check Microsoft 365/Outlook service status and your internet first.
• Confirm SMTP/IMAP settings for Telstra, Optus, iiNet or Microsoft 365.
• Fix NBN router issues: DNS, firewall rules, MTU and double‑NAT.
• Clear the Outbox, reset Send/Receive groups and repair PST/OST files.
• Antivirus, VPN and large attachments often block outgoing mail.

Outlook not sending emails: the quick Australian checklist

• Check Microsoft 365 and Outlook status; restart Outlook and your PC.
• Use the right SMTP port: 587 with TLS (avoid port 25, many ISPs block it).
• Telstra: smtp.telstra.com (465/587), imap.telstra.com (993). Optus: mail.optusnet.com.au (IMAP 993/SMTP 465/587). iiNet: mail.iinet.net.au (IMAP 993/SMTP 465/587).
• On NBN routers, set DNS to 1.1.1.1 or 8.8.8.8, and try MTU 1492 if sends stall.
• Work Offline, empty the Outbox, reduce big attachments, and send again.
• Run ScanPST on PST files or recreate corrupted OST files.
• Pause antivirus email scanning and disconnect the VPN to test.
• On mobile, update the Outlook app and re‑add the account.

What it is and core concept

Definition

Outlook is an email client that sends messages via SMTP and syncs mail with IMAP, POP or Microsoft Exchange. When people say “Outlook not sending emails,” it usually means SMTP isn’t authenticating, a firewall is blocking traffic, or a data file or router is misbehaving.

Why it matters

Brisbane homes and businesses rely on email for bookings, invoices and support. NBN outages, storm‑season power blips, and mixed ISP settings add extra wrinkles. A clear, local checklist gets you back to work quickly and avoids losing messages or time.

How it works and step-by-step

Process

Follow this clean flow:

• Check service status: Confirm Microsoft 365/Outlook and your ISP aren’t down. Try webmail to compare.
• Identify account type: Microsoft 365/Exchange, IMAP, or POP. Each has different settings and data files.
• Confirm SMTP/IMAP: Use Australian provider settings and ports. Use TLS/SSL. Avoid port 25.
• NBN router tune‑up: Reboot, set reliable DNS, check firewall, and test a different MTU (often 1492 for PPPoE).
• Outbox and groups: Switch Work Offline, move or delete stuck items, reset Send/Receive groups (Ctrl+Alt+S).
• Repair data: Run ScanPST on PST files. For Exchange/IMAP, recreate the OST by removing and re‑adding the account.
• Security apps: Temporarily disable antivirus email scanning and VPN/split tunnelling. Test send/receive.
• Mobile sync: Update Outlook app, re‑add the account, allow background data, and check battery/low‑power settings.
• Escalate: If mail still fails, it may be a server, DNS, account suspend, or corruption issue. Call a pro.

Featured answer

Restart Outlook and your NBN router, then test webmail. Check SMTP on port 587 with TLS and correct login. Clear stuck items by using Work Offline, then reset Send/Receive groups. If it still fails, repair the PST/OST, pause antivirus/VPN, and re‑test. Contact your provider if authentication keeps failing.

Common problems in Brisbane

Weather and infrastructure

• Summer storms and humidity can cause brief dropouts and corrupt Outlook data if a PC is powered off mid‑send.
• Older apartments in Fortitude Valley and Kangaroo Point often have double‑NAT or old routers that block SMTP.
• HFC areas like Carindale can see jitter at peak times, which breaks large outgoing emails.
• New estates in Springfield and North Lakes sometimes have default ISP DNS that times out on Microsoft servers.
• Logan and Redlands users report more brownouts during storm season, leading to OST/PST file repairs.

Troubleshooting and quick checks

Short answer

Test webmail and another device. Use SMTP 587/TLS and IMAP 993/SSL. Reboot your NBN router, switch DNS, and try Work Offline to clear the Outbox. Repair PST/OST, then test with antivirus and VPN off. If sends still fail, it’s likely a server, ISP block, or account issue.

Quick checks

Safe steps you can try now:

• Check Outlook’s bottom status bar for “Working Offline” or “Disconnected”.
• Microsoft 365: smtp.office365.com (587/TLS), outlook.office365.com (IMAP 993/SSL).
• Telstra BigPond: smtp.telstra.com (465/SSL or 587/TLS), imap.telstra.com (993/SSL).
• Optus: mail.optusnet.com.au (SMTP 465/SSL or 587/TLS; IMAP 993/SSL).
• iiNet: mail.iinet.net.au (SMTP 465/SSL or 587/TLS; IMAP 993/SSL).
• Attachment size: Keep under 20–25 MB. Compress files or share via cloud links.
• Outbox clear: File > Work Offline; open Outbox; delete or move stuck emails to Drafts; go back online.
• Reset Send/Receive: Ctrl+Alt+S > Edit > Un‑tick schedules > Close > reopen and re‑tick to refresh.
• PST repair: Close Outlook, run ScanPST.exe, repair, then restart.
• OST rebuild: File > Account Settings > Remove account > add it again to rebuild the cache.
• NBN router: Power‑cycle. Set DNS to 1.1.1.1 or 8.8.8.8. Try MTU 1492 if sends stall.
• Security: Pause antivirus email scanning; disconnect VPN; try again.

Safety notes and when to call a pro

Red flags

Stop and get help if:

• ScanPST reports repeated errors or your PST is over 10 GB and keeps corrupting.
• Passwords keep prompting even though webmail works (possible server or account suspend).
• Business mail is queuing for more than 30 minutes during work hours.
• You need to keep legal archives and can’t risk data loss.
• Router changes affect other staff or VoIP phones.

A tech can safely export mail, repair or split large PSTs, tune NBN routers, and test provider blocks without risking your data.

Local insights and examples

Brisbane/SEQ examples

Across Brisbane CBD and South Bank, we see Outlook timeouts fixed by switching DNS and enforcing SMTP 587/TLS. In Wynnum and Manly, salt air plus older modems often means flaky Wi‑Fi; a router swap clears Outlook sync issues.

In The Gap and Ashgrove, storms cause power flickers that corrupt PST files. We back up, run ScanPST, and set AutoArchive plus Online Archive for Microsoft 365. In Sunnybank and Eight Mile Plains, VPNs to overseas servers slow SMTP; split tunnelling restores speed.

Apartments in Newstead and Fortitude Valley frequently have double‑NAT from mesh routers. Bridging or using a single router allows proper SMTP authentication and stops stuck emails in Outbox. In Redcliffe and North Lakes, changing MTU to 1492 has resolved chronic send stalls after NBN provider swaps.

FAQs

Q1: Why are my emails stuck in the Outbox in Outlook?

Usually the SMTP connection is blocked, the attachment is too large, or Outlook is offline. Switch to Work Offline, open Outbox and move the message to Drafts. Check SMTP 587/TLS, reduce attachments, then go back online and send again.

Q2: What SMTP and IMAP settings should I use in Australia?

Common defaults: SMTP port 587 with TLS, IMAP 993 with SSL. Microsoft 365 uses smtp.office365.com and outlook.office365.com. Telstra uses smtp.telstra.com and imap.telstra.com. Optus and iiNet use their mail domains with the same ports. Avoid port 25.

Q3: How do I repair a corrupted Outlook PST or OST?

Close Outlook. Run ScanPST.exe on the PST and repair. For OST (Exchange/IMAP), remove the account in Outlook, then add it again to rebuild the cache. If errors repeat or the PST is very large, back up and split archives or call a technician.

Sources and further reading

Email works via SMTP (send) and IMAP/POP or Exchange (sync). ISPs often block port 25; modern setups use 587/TLS and 993/SSL. Outlook stores data in PST/OST; ScanPST repairs PST corruption. NBN routers affect mail via DNS, firewall rules, NAT and MTU size.

Wrap-up and next steps

If Outlook won’t send or receive, start with service status, correct SMTP/IMAP settings, and your NBN router. Clear the Outbox, reset Send/Receive, and repair the data file. If it still misbehaves, a quick remote session can sort it. Service:
Email Setup & Troubleshooting