Optimum email not working in Outlook

Question

Beginning of February my optimum account in outlook, on my laptop, started to sign me out. This is only happening on my laptop. I have Outlook on my PC and it's working fine except when I try to fix my laptop it will sometimes sign me out of my email on my PC. My PC will let me sign in with no problems after that. I have tried everything since then to try to fix the problem:

1. Clicked on Repair nothing happens, no wizard popup which I read would happen and it would just continually ask me to sign in.
2. Added a new profile
3. Removed all associated entries of my email in the Credentials Manager
4. Changed my password on all my devices and also on optimum.net, verified it worked in webmail.
5. Removed the account in Outlook, reinstalled and made sure all IMAP settings were correct.

Every once in a while my email would pop up and look fine in Outlook but as soon as I click on an email to open it I get signed out again and instead of seeing the email, I would see it for a hot second in the pane, and the it would say Access Denied.

I spoke to Optimum Tech Support and they had me try basically everything I already did a million times. They then found that there was an update KB5074109, which I see has been installed on my computer, that others were complaining they had similar issues after it was installed. They told me that there was another update, which was not installed on my laptop, KB5078127 that would correct the problem. I manually installed it but I am still having issues. Although I am not sure I installed the correct version, my system type is a 64-bit operating system, x64-based processor, it was the only one I think it would let me install, if I remember correctly. The others popped up with messages saying something to the effect they were not for my laptop. I did notice also that on my PC which is working fine with Outlook that those two updates were installed on it.

Please let me know if you know what is going on and how to fix this issue.

Thank-you

Answer 1

The behavior matches an Outlook profile/connection issue on that specific laptop rather than a general Optimum or update problem, especially since the same account works on the PC and via webmail.

Try the following on the laptop in this order:

1. Repair the Outlook profile from inside Outlook
   • In Outlook on the laptop, select File.
   • Select Account Settings > Account Settings.
   • On the Email tab, select the Optimum account and choose Repair.
   • Follow the wizard and then restart Outlook.
   • If the Repair button is missing or does nothing, proceed to step 2.
2. Use the Outlook connectivity troubleshooter
   • Run the classic Outlook for Windows connectivity troubleshooter from the same Windows PC where Outlook is installed: select the Start button in the article and follow the prompts in Get Help.
   • This will check and repair profile and connectivity issues specific to that machine.
3. Recreate the profile cleanly (if not already done this way)
   • Close Outlook.
   • Go to Control Panel > Mail > Show Profiles.
   • Add a new profile, configure the Optimum account, and set Always use this profile to the new one.
   • Start Outlook and test whether opening messages still triggers “Access Denied” or sign‑out.
4. Update Office and Windows on the laptop
   • In any Office app, go to File > Account > Update Options > Update Now to ensure Outlook has the latest fixes.
   • Run Windows Update on the laptop and install all pending updates so the Outlook/Windows components match the working PC as closely as possible.
5. If the issue persists only with this IMAP account
   • Confirm the account works in Outlook on the web or another device (already done via webmail and PC).
   • On the laptop, remove the Optimum account from Outlook again, restart Outlook, and add it back from scratch, letting Outlook auto‑discover settings where possible.

If Outlook on that laptop still signs out or shows “Access Denied” only for this account after these steps, the next escalation is to run the connectivity troubleshooter again and then contact Microsoft support with the results, since the same account and updates work correctly on the PC.

---

References:

• Fix your Outlook email connection by repairing your profile
• I can't send or receive messages in Outlook
• Outlook IMAP or POP server unexpectedly terminated the connection, and the server was interrupted
• Outlook and other apps are unable to connect to Outlook.com when using Basic authentication
• Outlook closes shortly after it is opened
• I get a "stopped working" error when I start Office applications on my PC