Issue Certificate can't be verified

[jonny_alex]

"The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect. If you see this message, it's usually caused by a mismatch in enabling SSL and the port number as entered in your Outlook account settings. "

This message occurs to me with all my clients that are using Outlook on their Computers.. The Settings are as Followed:

Server: imap.my-server-domain.ch (is also shown when i have to login to my plesk (srv01.domain.ch)
Port: 993
Encryption: SSL

Server: smtp.my-server-domain.ch (is also shown when i have to login to my plesk (srv01.domain.ch)
Port: 465
Encryption: SSL

Certificate to protect mail "Let's encrypt domain.ch"

DNS Zone Template (attached)

Mailserver Postfix & Dovecot

Plesk Version 18.0.23

How can i prevent this error to occur and to protect all clients with ssl?

And second.. Why does outlook not automatically detect settings? Is there a possibilty if someone with a domain on my page sets up Outlook, that all settings are getting imported automatically without further settings for the clients to do?

 

[Brujo]

this might help: How to secure a Plesk mail server with different SSL certificates (SNI support)

with Plesk Obsidian 18.0.23 comes a lot of new features arround mail which you can configure now. see "Highlights for the current build - Mail Auto-discovery and Mail Improvements"

for the second question see: How to manage mail autodiscover in Plesk Obsidian? based on the knowledge Article see the Warning: Outlook 2016/2019/Office 365 does not support autodiscover for IMAP/SMTP protocols.

 

[jonny_alex]

I can't solve this problem by myself, i'm really sorry but i would need someone to assist me with this issue.

Is there a easy step by step way to prevent this window to appear, at start in the future?
My clients are not satisfied, that they can't use ssl without always confirm to use the same server, when starting up outlook..

 

[jonny_alex]

This appears at every customer using the following settings:

 

[Brujo]

it seems you hit this issue: https://support.plesk.com/hc/en-us/...hen-connecting-account-hosted-on-Plesk-server