Issue Configuration Outlook with Plesk, certificate error

[lvrconseil]

Hi,

I have a VPS SSD by ovh with Plesk Web Admin 17.5.3. This Plesk manages the dns area of my domaine name. I installed Let's Encrypt for secure my website and webmail.

If i go to my webmail, it is ok, but if i configure a email client (test with Outlook 2013 and Thunderbird in IMAP), i had a alert form certificate. It does not detect the certificate of let's encrypt but that of plesk... (see picture)

How can I fix the problem?

Regards,

Luc

 

[Monty]

Go to Tools & Settings => SSL/TLS Certificates and make sure you have selected the Let's Encrypt certificate where it says "Certificate for securing mail".

 

[lvrconseil]

Hi Emmanuel,

Thank you for your answer, I checked and actually the certificate used was that of plesk, once changed to let's encrypt it works if i used mondomaine.fr as incoming / outgoing server.

If i want to use mail.mondomaine.fr what sould i do?

 

[Monty]

Short answer: Do not use mail.mondomaine.fr in your mail client, stick to mondomaine.fr for both incoming and outgoing server.

Long answer: The thing is that the Let's Encrypt certificate has been issued for mondomaine.fr (and probably www.mondomaine.fr) so you will get a certificate error when you connect with mail.mondomaine.fr in your mail client.

If you have only one domain on your VPS and the subscription belongs to the Plesk admin user then you could try this:
* Create a subdomain "mail.mondomaine.fr" in your existing hosting
* Make sure the DNS A record for "mail.mondomaine.fr" is pointing to the same IP as "mondomaine.fr"
* Secure this subdomain with a Let's Encrypt certificate
* Go to Tools & Settings => SSL/TLS certificates and pick the new certificate ("Let's Encrypt mail.mondomaine.fr") for the mail server

Not sure if this will work but you could give it a try.

Note: This will only work for one domain. You can't have multiple certificates for your mail server if you only have one IP address on your VPS.
Please also see the ongoing discussion here:
Input - Add multidomain-support to Let´s Encrypt Certificate used for the mailserver