SOLVED Outlook Imap configuration errors after Exim update

Operating System & Version
CentOS v7.9.2009 STANDARD vmware
cPanel & WHM Version
108.0.14

iTecan

Member
May 7, 2020
15
1
3
Spain
cPanel Access Level
Root Administrator
Hello,

one month ago we detected a problem with Outlook client when trying to configure an IMAP account, at first we thought that it was focused on only one domain account but we have noticed that this problem happens in all accounts in our server.
This error is happening after the update of cPanel to version 108.0.14 which includes Exim update to version 4.96

After opening a ticket (id 94745787) we only get the following error in the logs:

2023-03-13 12:12:35.515 [29844] TLS error on connection from [95.122.37.227]:49244 I=[185.103.38.175]:465 (SSL_accept): ret 5

We check the following article Outlook TLS error: None of the authentication methods supported by this client are supported by your server. and include all the recommended options to add more ciphers to SSL but with no luck.


The clients where we tried to configure the email account with errors using IMAP protocol are:

OS: Windows 10
Mail client: Outlook 2019, Outlook 2021
We can configure the email account correctly using:

POP3 protocol
IMAP protocol using Outlook Safe Mode

When trying to use IMAP protocol in Outlook Normal Mode we get the error but the test message from outlook is sent and we can see it in Webmail.


Using the following clients we were able to configure IMAP protocol with no problem at all.

OS: Android 13 One UI 5.1
Mail client: Outlook, Gmail
OS Windows 10
Mail client: Windows 10 Mail Application

This problem has not happened to us using the Outlook client on Windows at any time in the past, so we assume it is related to the latest update of our server.
 

iTecan

Member
May 7, 2020
15
1
3
Spain
cPanel Access Level
Root Administrator
UPDATE:

After more testings we tried stoping the integration of ESET End Point Antivirus with Microsoft Outlook that includes an Addon, after this test we were able to configure in Outlook the email account with no problem.