This is the typical message received: Task 'yourdomainname.com - Receiving' reported error (0x80042108): 'Outlook is unable to connect to your incoming (POP3) e-mail server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).'
This error occurs if Outlook cannot connect to the mail server, in most cases, when your anti-virus or any security shield (eg. firewall, port blocker) behaves unexpectedly. It can happen when installing/updating Outlook or due to corrupt configuration files, registry values and system files.
To resolve this issue, please try the following:
1.
Uninstall Anti-virus integration
If you have an anti-virus installed which integrates itself with Outlook, uninstall the integration part of your anti-virus or uninstall the anti-virus completely and try again. Typically an anti-virus software integrates an add-in into Outlook to scan email. To remove the add-in:
a. Go to Outlook > File > Options > Add-ins
b. Select Manage: Com Add-ins and click on the Go button
c. Now select all the add-ins related to your anti-virus or any other security shield and click on the Remove button.
d. Close Outlook and restart your PC.
e. Check if it solves your issue. If not, try again after uninstalling all anti-virus and security software.
2.
Allow Outlook through Windows Firewall
If Outlook is blocked in your Firewall, it will deny all incoming and outgoing traffic for Outlook and you won’t be able to send or receive any email using Outlook. To allow Outlook in Windows Firewall:
a. Open Start > Windows Defender Security Center > Firewall & Network Protection > Allow an app through firewall
b. Click on Change Settings.
c. Ensure that the Private and Public checkboxes are selected for Microsoft Office Outlook.
d. Click OK.
e. Try to send/receive email now.
3.
Make sure the ports are open and the mail server hostname is not blocked in your network firewall
If you are using any firewall in your local network, make sure 26, 110, 993, 995 and 465 ports are open. and yourdomainname.com or prefix01.servername.com is not blocked.
4.
Repair OUtlook's PST files
To repair any corruption in outlook data files:
a. Go to Outlook > File > Account Settings > Data Files
b. Double click on a data (PST) file
c. Click Repair.
Above are the most common suggestions to resolve the issue. If those didn't solve your issue, please visit Microsoft's official support articles for recommended solutions:
1. http://support.microsoft.com/kb/813514
2. https://answers.microsoft.com/en-us/msoffice/forum/msoffice_outlook-mso_other/reported-error-0x80042108-outlook-is-unable-to/188e5495-c209-41a3-a334-5efc3f4ccd59
