Outlook error fix · Classic Outlook (Windows)
Fix Outlook Error 0x800ccc90
Outlook error 0x800ccc90 means the mail server rejected your POP3 login — your username or password wasn't accepted. It often appears right after a password change. The fix is to re-enter your full email address as the username, use the correct (or app) password, confirm port 995 with SSL, and make sure POP is switched on in your mailbox.
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What error 0x800ccc90 actually means
The message that comes with it is usually "Your incoming (POP3) server rejected your login." In plain English, Outlook reached the server fine — but the username or password it sent wasn't accepted, so nothing downloads.
Because it's a login problem rather than a connection problem, the usual triggers are:
- Your email password was recently changed and Outlook is still using the old one — a common cause.
- The username isn't your full email address (some servers need the whole address, not just the bit before the @).
- Your provider (such as Gmail or Yahoo) no longer accepts your normal password in Outlook and needs an app password instead (Gmail only offers one once 2-Step Verification is on).
- POP access is switched off in your mailbox's settings, so the server refuses POP logins entirely.
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// FIX IT WITH ME · STEP BY STEP
Fix it with me, one step at a time
The steps from this guide, one at a time, in the order that fixes the most cases fastest. Tell it what happened and it shows the next step. Nothing here leaves your device.Last reviewed 6 October 2026
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01Open Account Settings
Go to File > Account Settings > Account Settings, select your POP account on the Email tab and click Change.
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02Check username and password
Make sure the User Name is your full email address, then carefully retype your current password — a stale password after a change is a common cause.
Is it working now? -
03Use an app password if required
If your provider is Gmail or Yahoo, generate an app password (Gmail needs 2-Step Verification on first) on their security page and paste it in instead of your normal password.
Is it working now? -
04Confirm incoming port and encryption
Click More Settings > Advanced and set the incoming POP3 server to port 995 with SSL/TLS, and the outgoing SMTP to port 587 with STARTTLS (or 465 with SSL if your provider lists that, as BT does) with outgoing authentication ticked.
Is it working now? -
05Enable POP in your mailbox
Sign in to your provider's website and confirm POP access is switched on in its settings, otherwise the server refuses all POP logins.
Is it working now? -
06Test the settings
Click Test Account Settings and confirm the incoming (POP3) test passes with a green tick.
Is it working now?
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Fix Outlook Error 0x800ccc90 - the fix order (365techies.co.uk/outlook-error-0x800ccc90/) 1. Open Account Settings: Go to File > Account Settings > Account Settings, select your POP account on the Email tab and click Change. 2. Check username and password: Make sure the User Name is your full email address, then carefully retype your current password — a stale password after a change is a common cause. 3. Use an app password if required: If your provider is Gmail or Yahoo, generate an app password (Gmail needs 2-Step Verification on first) on their security page and paste it in instead of your normal password. 4. Confirm incoming port and encryption: Click More Settings > Advanced and set the incoming POP3 server to port 995 with SSL/TLS, and the outgoing SMTP to port 587 with STARTTLS (or 465 with SSL if your provider lists that, as BT does) with outgoing authentication ticked. 5. Enable POP in your mailbox: Sign in to your provider's website and confirm POP access is switched on in its settings, otherwise the server refuses all POP logins. 6. Test the settings: Click Test Account Settings and confirm the incoming (POP3) test passes with a green tick. Still stuck? 365 Techies fix it remotely: 01202 775566 - https://365techies.co.uk/remote-support/// NEED THIS FIXED RIGHT NOW?
Skip the DIY — call 01202 775566 and we can be looking at your screen within minutes. You watch everything we do, and most problems on this page are fixed in one short remote session. (Mon–Fri, 9am–5pm.)
Step by step
How to fix it in classic Outlook (Windows)
Work through these in order. If you know your password changed, start at step 2.
- Open your account settings. Go to File > Account Settings > Account Settings. On the Email tab, select your POP account and click Change.
- Check the username and password. Make sure the User Name is your full email address (for example you@your-domain.com, not just "you"). Then retype your current password carefully — a stale password after a recent change is a common cause of this error.
- Use an app password if your provider needs one. With providers such as Gmail or Yahoo, your normal password won't work here (Gmail only offers app passwords once 2-Step Verification is on). Generate an app password on the provider's security page and paste that in instead.
- Confirm the incoming port and encryption. Click More Settings > Advanced and set the incoming server (POP3) to port 995 with SSL/TLS. Check the outgoing (SMTP) side too — port 587 with STARTTLS (or 465 with SSL if that is what your provider lists, as BT does) and, on the Outgoing Server tab, tick "My outgoing server (SMTP) requires authentication".
- Make sure POP is enabled in your mailbox. Sign in to your email provider's website and check that POP access is switched on in its settings — if POP is disabled there, no password in the world will let Outlook log in.
- Test the settings. Back on the change screen, click Test Account Settings. The incoming (POP3) test should now pass with a green tick.
Re-entering your password and correcting the port doesn't touch your existing mail. If we ever need to rebuild a POP profile, your messages already downloaded stay in your data file — we always back up first before any bigger change.
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// GOOD QUESTIONS
Frequently asked
Why does 0x800ccc90 say my POP3 login was rejected?
It means Outlook reached the server but the username or password it sent wasn't accepted. Check that your username is your full email address and retype your current password. If your provider is Gmail or Yahoo, you'll need an app password rather than your normal login (Gmail needs 2-Step Verification on first).
It started right after I changed my password — is that why?
Almost certainly. Outlook keeps using the old saved password until you update it, and the server rejects it. Go to File > Account Settings > Account Settings, select the account, click Change and retype the new password. It is a common cause of 0x800ccc90.
Should my username be my full email address?
For most POP accounts, yes. Many mail servers expect the whole address (you@your-domain.com) as the username, not just the part before the @. If in doubt, enter the full email address in the User Name field on the account's Change screen.
Which port should POP3 use, and does it need SSL?
Use incoming POP3 port 995 with SSL/TLS for a secure connection. You'll find this under More Settings > Advanced. On the sending side, use SMTP port 587 with STARTTLS (or 465 with SSL if your provider lists that, as BT does) and tick 'My outgoing server (SMTP) requires authentication'.
What if POP is turned off in my mailbox?
Some providers disable POP access by default. If it's off, the server refuses every POP login regardless of your password. Sign in to your provider's website, open its mail or forwarding settings, and switch POP access on, then test again in Outlook.
Can 365 Techies fix 0x800ccc90 for me remotely?
Yes — it's a fast fix for us. We connect securely with Splashtop SOS (you watch the session, we phone you first, and access ends the moment we finish), sort your username, password and POP settings, and get mail downloading again the same day. Call 01202 775566.
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Still getting 0x800ccc90?
We'll connect securely, sort your login and POP settings and get mail downloading again — usually within minutes. You watch the whole session, we phone first, and access ends the moment we're done.
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