hello dears

belalm

i have a mailcow server after i had renewed the ssl certificate the message still appeared with the outlook on the 16 computers that i have ( the server you are connected to is using a security certificate that cannot be verified . the target principal name is incorrect . do you want to continue using this server) how can i solve this from server

esackbauer

How shall we know? Please describe your setup in more detail. Are you using a reverse proxy? where was the ssl certificate generated?

belalm

esackbauer no i didn’t use reverse proxy . i had only renew the lets’s encrypt ssl certificate and it reflects on the url and is ok . but i hav 16 computers all appear the attached message so i don’t know what should i do

esackbauer

Again: Where did you renew the lets encrypt cert? With mailcows internal ACME client?

Which protocol is Outlook using to access mailcow? IMAP or ActiveSync?

Are you using cloudflare?

belalm

i renewed it on the ubuntu server which contain the maicow . i use IMAP , yes i am using cloudflare

esackbauer

belalm i renewed it on the ubuntu server which contain the maicow .

So you are not using mailcows internal ACME Client. THat is where your problem comes from.

You need to copy the SSL certificates from ubuntu server to mailcow:
https://docs.mailcow.email/post_installation/firststeps-ssl/#how-to-use-your-own-certificate

And you need to do it each time you renew the certificates on the ubuntu server.

belalm

i can’t do that please guide me as it is my first time dealing with mailcow
so sorry

esackbauer

You have to do it yourself, its well documented. Running a mailserver without any knowledge is a really bad idea, its one of the most complex services you can run. And Lets Encrypt/SSL certificates are nothing specific to mailcow.
I would suggest you reach out to the folks of servercow.de and have them resolve this for you, or you change to their managed hosting.