When Outlook, Thunderbird or Apple Mail stops working with your hosting mailbox, the cause is usually one of three things: a setting that doesn't match, a password that changed, or a problem inside the app itself. This page gives the quick checks for each app. First confirm the settings, then use the app-specific fixes below.
For mailboxes on cPanel, DirectAdmin, Webuzo and Windows (Plesk) hosting, use mail.yourdomain.com for incoming and outgoing mail, IMAP on 993 and SMTP on 465, both with SSL/TLS, your full email address as the username and SMTP authentication on. Test the password in webmail: if webmail works, the problem is in the app. Then try the app's own repair tools, such as Outlook's safe mode, Thunderbird's Compact or Apple Mail's Rebuild.
Settings and setup for every app: Email client settings for popular email clients. Every email symptom, from mail not arriving to messages going to spam: Email troubleshooting.
1. Check the settings first
| Setting | cPanel, DirectAdmin and Webuzo | Windows (Plesk) |
|---|---|---|
| Incoming and outgoing server | mail.yourdomain.com | mail.yourdomain.com |
| IMAP (recommended) | 993, SSL/TLS | 993, SSL/TLS |
| POP3 | 995, SSL/TLS | 995, SSL/TLS |
| SMTP (recommended) | 465, SSL/TLS | 465, SSL/TLS |
| SMTP alternative | 587, STARTTLS | Not available: port 587 is closed |
| Username | Your full email address | Your full email address |
| SMTP authentication | Required | Required |
- The password is the mailbox password, not your control panel or client area password.
- Test it in webmail. The addresses are in how to log in to webmail. If the password fails there too, reset it in your control panel.
- Certificate warning? In cPanel, Email › Email Accounts › Connect Devices shows the exact server name for your account.
These ports were measured as open on our shared servers on 20 September 2026. Business Email is a separate product with its own settings; see Business Email client setup.
2. Microsoft Outlook
- Check the outgoing server. If Outlook receives but will not send, open the account's server settings and make sure the outgoing server requires authentication, using the same settings as incoming.
- Update Outlook. In classic Outlook, go to File › Office Account › Update Options › Update Now. The new Outlook updates on its own.
- Start in safe mode (classic Outlook). Close Outlook, press Windows + R, type
outlook.exe /safeand press Enter. If the problem disappears, turn off add-ins one by one under File › Options › Add-ins. - Repair the data file (classic Outlook). Close Outlook and run the Inbox Repair Tool,
SCANPST.EXE, from your Office installation folder, then choose your.pstfile. For an IMAP account, it is usually quicker to remove the account and add it again, because the mail is still on the server. - Remove and re-add the account if the settings look right but nothing works.
Step-by-step screens: how to configure Outlook.
3. Mozilla Thunderbird
- Update Thunderbird from Help › About Thunderbird.
- Compact folders. Right-click a folder and choose Compact. This frees space after many deletions and fixes some slow or stuck folders.
- Repair a folder. Right-click the folder, choose Properties and click Repair Folder to rebuild its index.
- Start in troubleshoot mode from Help › Troubleshoot Mode to rule out add-ons.
- Recheck the server settings under Account Settings, or remove the account and add it again.
Step-by-step screens: how to configure Thunderbird.
4. Apple Mail on a Mac
- Check the connection settings. Go to Mail › Settings › Accounts, select the account and open Server Settings. Untick Automatically manage connection settings and confirm 993 for incoming and 465 for outgoing, both with TLS/SSL. On older macOS versions, Settings is called Preferences.
- Rebuild a mailbox. Select the mailbox, then choose Mailbox › Rebuild. Mail downloads the messages again from the server.
- Update macOS from System Settings › General › Software Update. Apple Mail updates with macOS.
- Take the account offline and online again from the Mailbox menu if it shows as offline.
Older guides suggested turning off your firewall or antivirus to test a mail app. Don't: it exposes your computer and rarely helps. If you suspect security software, look for its "email scanning" option and check it is not intercepting ports 993 or 465. Also, after changing a mailbox password, update it on every device. A phone that keeps trying the old password causes repeated failed logins, and the server firewall then blocks that network's IP address automatically.
5. Still stuck?
Check whether mail works on another device or network: if it works on mobile data but not on office Wi-Fi, that network's IP address may be blocked after failed logins. Eudora, which older guides covered, stopped being developed many years ago; move to a current app such as Thunderbird, Outlook or Apple Mail. Microsoft, Mozilla and Apple also publish support pages for their own apps.
Frequently asked questions
What server settings should my email app use?
For mailboxes included with cPanel, DirectAdmin, Webuzo or Windows (Plesk) hosting, use mail.yourdomain.com for incoming and outgoing mail, IMAP on port 993 and SMTP on port 465, both with SSL/TLS, your full email address as the username and SMTP authentication on.
Why can my email app receive but not send?
Usually because SMTP authentication is off or the outgoing port and encryption do not match. Set the outgoing server to mail.yourdomain.com on port 465 with SSL/TLS, and use your full email address and password for the outgoing server too.
My password works in webmail but not in Outlook. What is wrong?
The problem is in the app's settings, not the mailbox. Check that the username is your full email address and that the ports and encryption match, then remove and re-add the account if it still fails.
Why did my email stop working on every device on my office network?
A device that keeps trying an old password causes repeated failed logins, and the server firewall can then block that network's IP address. Update the password on every device, then contact support to check for a block.
Should I turn off my firewall to fix an email problem?
No. Turning off a firewall or antivirus exposes your computer and rarely fixes mail. Check the app's settings and test in webmail first, and if you suspect security software, check its email scanning option.
Ready to fix it? Compare your app with the email client settings, work through email troubleshooting, or open a ticket with your email address, app, device and the exact error.
Tell us your email address, the app and device, and the error you see, and we will check it with you.
Open a support ticket