Email Not Delivering? How to Find the Cause and Fix It
Updated: 12 hours ago
When an email won’t deliver, the fault sits in one of three places: your device or app, your outgoing mail server, or the recipient’s server. Look at what happened to the message. Did it sit in the Outbox, throw an error straight away, bounce back later, or show as “Sent” and then vanish? That one clue usually points to the fix. This guide walks you through each case in plain English, in the order we’d check them on a home visit.
TL;DR
Work out where the message stopped: stuck in the Outbox, an instant error, a bounce-back, or “Sent” but never received.
Stuck or erroring on your side is usually a connection, a changed password, a big attachment or wrong outgoing server settings.
A bounce-back message tells you the reason. Read it, because it often names a mistyped address, a full mailbox or a rejection.
“Sent” but never arrived usually means spam filtering, a rule, or a problem on the recipient’s end. Ask them to check Junk.
If you’ve worked through the checks and it still fails, we can sort it at your home in Brisbane, Logan, Ipswich or Redlands.
Table of Contents
Start by working out where the email stopped
Before you change any settings, spend two minutes on diagnosis. Changing settings at random is how a small fault becomes a big one.
There are four common patterns:
What you see | Where the fault usually sits | Start here |
Message sits in the Outbox or says “Sending” for ages | Your device, connection or app | Internet, attachment size, outgoing server settings |
An error pops up as soon as you press Send | Your account or outgoing server | Password, sending limit, server settings |
A bounce-back message arrives in your inbox | The recipient’s address or server | Read the message, check the address |
It says “Sent” but the recipient never gets it | Spam filtering or a rule on the other end | Sent folder, then ask the recipient to check Junk |
The keyword people type is “email not delivering”, but there’s a real difference between an email that never left your device and one that left and got refused. Fixing the wrong one wastes an afternoon.
Step 1: Rule out the quick, boring causes
Most failed emails come down to something simple. Check these first, in this order.
Is the address correct?
One wrong letter, a missing dot or “gmial” instead of “gmail” is the most common reason an email fails. Retype the address rather than eyeballing it. If you replied to an old message, the contact may have changed address since. Also remember the address has to exist. A correctly spelled address for a mailbox that was closed will still bounce.
Are you actually online?
If your Wi-Fi has dropped, your email app can’t talk to the server. Open a website on the same device. If that fails too, the problem is your connection, not your email. Our guide on fixing “connected, no internet” Wi-Fi covers testing one device first, and the same logic applies here.
In Outlook, look at the status bar at the bottom of the window. If it says Disconnected, Working Offline or Trying to connect, Outlook can’t reach your mail server. On the Send/Receive tab, check whether Work Offline is switched on, and toggle it.
Is the message stuck in the Outbox or Drafts?
Open the Outbox. If your email is sitting there, it never left. Often a single oversized or corrupt message blocks everything behind it. We’ve written a separate walkthrough on fixing an email stuck in the Outbox. Also look in Drafts. If your message is there, it was never sent at all. If it’s in neither, check Sent. If it’s in Sent, your side did its job.
Is the attachment too big?
Every provider limits message size, and the limit differs between them. Photos straight off a phone, a scanned PDF or a video can easily push a message over. A stuck large message can also hold up every message you send after it. Test by sending a short plain-text email to the same person with no attachments. If that goes through, the attachment was the problem. Compress the files or share them through a cloud storage link instead.
Step 2: Check your account and sending limits
If the message isn’t stuck and the address is right, look at your account.
Did your password change?
If you changed your email password on your phone or in webmail, your laptop’s email app might still be using the old one. It then fails to send, sometimes without a clear message. Update the saved password in the app. A quick test: log in to webmail in a browser with your current password. If webmail works and the app doesn’t, the app’s saved details are out of date.
Have you hit a sending limit?
Every mail provider caps how many messages or recipients you can send to in a day. Reach the cap and sending pauses, often for up to 24 hours. Providers also pause sending when something looks unusual, such as a sign-in from a new location or a sudden burst of outgoing mail. Brand new accounts often have lower limits that rise as the account builds a track record.
This catches people sending to a big family list, a club or a school group. If that’s you, send in smaller batches, and use a proper mailing tool for large lists instead of one giant Cc or Bcc.
Is the mailbox full?
A full mailbox can stop you receiving mail, and with some providers it affects sending too. Check how much storage you’ve used. If you’re on Gmail, our guide to reclaiming Gmail storage takes under 30 minutes. It also explains when it’s worth getting a technician in.
Is a rule moving or deleting mail?
Inbox rules and filters can quietly send mail to another folder, forward it elsewhere or delete it. Open your rules or filters settings and look for anything you don’t recognise. Check blocked sender lists in the same place. This matters most for messages you’re receiving but it can also explain why your Sent items look odd. Also check that your account is set to save sent messages. If it isn’t, you won’t see a copy even when the email went out fine.
Step 3: Check the settings your email app uses
If webmail works but your app (Outlook, Apple Mail, Windows Mail, or the mail app on your phone) won’t send, the app’s outgoing server settings are the likely cause. This is one of the most common reasons an app refuses to send.
The things to verify are:
Outgoing (SMTP) server name: it must match what your provider gives you. A single typo breaks it.
Port: your provider will list the right one for outgoing mail.
Encryption: SSL/TLS or STARTTLS, as your provider specifies.
Username: usually your full email address.
Password: the same one you use for webmail.
Authentication: the outgoing server must be set to require it. If this box is unticked, many servers will refuse your mail.
Your provider’s help page lists the exact values. If you’re with an Australian internet provider, search for its email settings page and copy the values character by character.
Two other things can interfere. A VPN may give you an internet address that your mail provider has blocked. Antivirus or firewall software can also block email connections. To test, turn the VPN off and try again. If you suspect your security software, don’t disable it permanently. That’s a job for someone who can check it safely.
Step 4: Read the bounce-back message
A bounce is actually good news in a way: the system is telling you why it failed. Most people delete these without reading. Don’t.
A bounce usually arrives from an automated sender, often named something like Mail Delivery Subsystem or Postmaster, with a subject such as “Delivery Status Notification (Failure)” or “Undeliverable”. Scroll past the corporate wording and look for the line that states the reason.
Temporary versus permanent
Most bounces carry a numeric code. As a rule of thumb, a code starting with 4 means a temporary problem. The server may keep retrying for a while, and sending again later often works. A code starting with 5 means a permanent refusal. Resending the same message unchanged won’t help. You need to change something: the address, the size, the attachment or the way you send it.
What common bounce messages mean
Message says | What it usually means | What to do |
User unknown, address not found, recipient rejected | The address doesn’t exist or is mistyped | Check spelling, confirm the address with the person another way |
Host or domain not found | The domain after the @ is wrong or has no mail setup | Check the domain spelling |
Mailbox full, over quota | The recipient has no storage left | Tell them another way, try again later |
Message too large | Attachments exceed a size limit | Shrink files or share a link |
Blocked attachment | The file type is refused | Zip it or share via cloud storage |
Authentication failed | Wrong username or password in your app | Update saved password, check settings |
Relay access denied | Your outgoing server isn’t accepting you | Turn on outgoing authentication, check the From address |
Connection timed out | Network, firewall or server trouble | Check your internet, try webmail |
Message rejected, spam suspected, client host rejected | The receiving server blocked your message or your sending address | Simplify content, remove odd links, see the next section |
Daily limit exceeded | You’ve hit your provider’s cap | Wait up to 24 hours |
If you’re still stuck after trying again later and checking the address, contact the recipient’s email provider. They can see their side of the failure, and you can’t.
Step 5: When it says “Sent” but never arrives
This is the most frustrating case. Your app shows no error, yet the recipient swears nothing came.
Work through it like this:
Check your Sent folder and Drafts. If it’s in Sent, it left your account. If it’s in neither, it may have been deleted before sending.
Wait a few hours. Sometimes a delivery error message turns up later.
Ask the recipient to check Junk or Spam. This is the most likely answer. Ask them to mark your message as not spam and add you to their contacts.
Ask them to check filters, rules and blocked addresses. Their own settings may be hiding you.
Check the address once more. A typo that happens to be a real address means your email went to a stranger.
Try a different route. Send a short plain-text message from webmail. If that arrives, the issue is with your app or its content.
If you also receive bounce-backs from many different people, or the problem affects only certain recipients’ providers, the issue may be your sending reputation or the way your domain is set up.
Step 6: If you send from a business or custom domain
Emails from a custom address (you@yourbusiness.com.au) have an extra layer that can fail. Receiving servers look at whether your domain is set up to prove its mail is genuine, using records called SPF, DKIM and DMARC. If those are missing, wrong, or out of date after a change of provider, receiving servers may send your mail to Junk or reject it. A sender whose mail server has landed on a blocklist can also find that messages are refused at the door.
If you manage your own domain, improving email deliverability is worth reading: it explains how authentication and sender reputation work, written for people sending real mail rather than engineers. One rule of thumb applies whatever you read: don’t randomly edit DNS records. A wrong change can stop all your email, including mail you receive. If your web designer or host set up your domain, ask them what’s configured before touching anything.
If you want a record of what you’ve sent, a simple habit helps. Bcc yourself on important messages, such as quotes and invoices. Keeping a copy of every invoice you send shows how a Bcc copy gives you proof that a message left your account, which is handy when someone says it never arrived.
Step 7: Quick tests that narrow things down fast
These take a minute each and tell you a lot:
Try webmail. If webmail sends but your app doesn’t, the fault is in the app or its settings.
Try another device. If your phone sends but your laptop doesn’t, it’s the laptop.
Try another network. Switch from home Wi-Fi to mobile data. If it works, the problem is your home network or router.
Send to a different recipient. If mail goes to some people but not others, the cause is likely on their end.
Send a plain-text test. No attachments, no images, one line. If it works, something in the original message was the trigger.
Check your provider’s status page. Outages and scheduled maintenance do happen, and nothing on your side will fix them.
The pattern from these tests often gives the answer before you’ve touched a setting.
When to stop and call someone
Some email problems are quick to fix. Others are tangled with your device, network and account all at once. It’s worth getting help when:
The Outbox is stuck and clearing it doesn’t help.
Your email app keeps asking for a password that you know is right.
You get bounce-backs you can’t make sense of.
Email broke after a new computer, a new router or a change of internet provider.
You’re getting unusual bounce messages for emails you never sent, or contacts report strange emails from you. That can point to a compromised account, and you should change your password promptly and get proper help. Our scam protection and cyber security service covers exactly this.
You need email working across a laptop, phone and tablet at once.
Also consider the cost of your time. If you’ve spent an hour going in circles, a technician who has seen the same fault many times will often spot it in minutes.
Get it fixed at home in Brisbane
We’re NextGen IT, and we fix email problems at your door across Brisbane, Logan, Ipswich and Redlands. Our technicians check your account, app settings, connection and devices, then explain what was wrong in plain English, with no jargon. We offer same-day home visits, and our “No Fix, No Fee” guarantee means you pay only when we get the problem resolved.
Our email setup and support service covers setting up accounts, fixing send and receive errors, resolving sync problems between devices and clearing stuck messages. If the real cause turns out to be your connection, we can look at that on the same visit through our Wi-Fi and internet support, and if you use a Mac or iPhone, our Apple support covers those devices too.
Keeping email working once it’s fixed
A few habits prevent most repeat problems:
Update the saved password in every app and device whenever you change it.
Keep your mailbox tidy so you don’t hit your storage limit.
Share big files by link rather than attachment.
Check your rules and filters now and then, especially if you didn’t create them.
Keep your operating system and email app up to date.
Use a strong, unique password for your email account. It’s the key to most of your other accounts.
Save the exact outgoing server details your provider gave you somewhere safe.
If Outlook is giving you other trouble, such as slow or empty results, our guide to fixing Outlook search covers six quick checks.
FAQ
Why are my emails sending but not delivering?
The message left your account but was stopped or hidden on the other side. The usual causes are spam filtering, a rule or blocked-sender list on the recipient’s account, a full mailbox, or a mistyped address that happens to exist. Ask the recipient to check Junk and add you to their contacts. Then check your Sent folder to confirm it did leave.
Why do my emails bounce back?
A bounce means the receiving server refused the message and told you why. Common reasons are a wrong or non-existent address, a full mailbox, a message that’s too big, a blocked attachment, or the recipient’s server rejecting it as suspected spam. Read the reason in the bounce message itself. A temporary failure may work if you try again later, while a permanent one needs something changed.
Why is the recipient not receiving my emails?
Start with the basics: confirm the address, then ask them to check their Junk or Spam folder and any filters. If only one person or one provider is affected, the problem is probably on their side, and their email provider can look into it. If lots of people miss your mail, check your own sending settings or your domain setup.
Why are my emails not sending at all?
The most common causes are no internet connection, a message stuck in the Outbox, a changed password, wrong outgoing server settings, a sending limit or an oversized attachment. Test by sending a short plain-text email from webmail. If webmail works, the problem is in your email app or its settings.
Can you fix email problems at my home?
Yes. We visit homes in Brisbane, Logan, Ipswich and Redlands, check the account, app, devices and connection, and explain the fix in plain language. Our “No Fix, No Fee” guarantee means you only pay when we resolve the problem.
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