Let us examine the error Outlook cannot connect via TLS to a Plesk server. With the support of our Plesk support services at Bobcares we can give you a complete note on to remove the error.

Error: Outlook cannot connect via TLS to a Plesk server: Symptoms

Below given are the symptoms for the error

• With a Windows upgrade,  cannot connect to a Plesk server through TLS (KB5018410).
• Outlook gives the 0x800CCC80 or 0x800CCC1A errors.

Causes for the Error: Outlook cannot connect via TLS to a Plesk server

KB5018410 disables the use of secure SMTP. TLSv1 and TLSv1.1 are likewise disabled by default.

Error Resolution

Install one of the following updates on the client’s computer, depending on the operating system version. This might clear the cannot connect via TLS to a Plesk server error:

• Windows 11, version 21H2: KB5018496
• Windows 10, version 20H2; Windows 10, version 21H1; Windows 10, version 22H1; Windows 10 Enterprise LTSC 2021: KB5020435
• Windows Server 2022: KB5020436
• Windows 10 Enterprise LTSC 2019; Windows Server 2019: KB5020438
• Windows 8.1; Windows Server 2012 R2: KB5020447
• Windows Server 2012: KB5020449

If the update is not available through Windows Update Center, we can download and install it from the Microsoft Update catalog.

Instead, one of the workarounds listed below can be used for removing the cannot connect via TLS to a Plesk server error:

• One

  Add option -o tls_ssl_options=NO_TICKETinto the/etc/postfix/master.cfto Turn off the TLS Session Resumption feature.
• Two

  Revert the KB5018410 upgrade on a client’s Computer.

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Conclusion

To sum up we have now gone throgh the Outlook cannot connect via TLS to a Plesk server error. With the support of our Plesk support services, we have learned to remove the error.