Question Help request: SSL certificate seems to have trust issues. How to resolve?

[MHC_1]

Server operating system version

Ubuntu 22.04.4 LTS

Plesk version and microupdate number

Version 18.0.61 Update #5

We have a new server on Plesk Obsidian 18.

In this there is SSL it! Which we have used for a number of domains on the server . However one domain is showing persistent inconsistencies with the certificate and we are unable to resolve this.

The website domain works fine, and presents no issues but email connection to the domain presents that the certificate is invalid.

Result from TLSCheck online web checker.
Checking domain.co.uk from www12-do.checktls.com(V03.74.00) at 2024-07-01T10:46:07Z:

seconds		lookup	result
[000.000]		DNS LOOKUPS
[000.008]		SEARCHLIST	104.131.118.216,134.209.169.224,1.1.1.1,8.8.8.8,67.207.67.3
[000.167]		MX-->domain.co.uk	(0) domain.co.uk
[000.245]		MX:A-->domain.co.uk	123.456.678.789

seconds		test stage and result
[000.000]		Trying TLS on domain.co.uk[123.456.678.789:25] (0)
[000.075]		Server answered
[000.170]	<‑‑	220 server.co.uk ESMTP Postfix
[000.171]		We are allowed to connect
[000.171]	‑‑>	EHLO www12-do.checktls.com
[000.246]	<‑‑	250-server.co.uk 250-PIPELINING 250-SIZE 10240000 250-ETRN 250-STARTTLS 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250-DSN 250 CHUNKING
[000.246]		We can use this server
[000.246]		TLS is an option on this server
[000.247]	‑‑>	STARTTLS
[000.321]	<‑‑	220 2.0.0 Ready to start TLS
[000.321]		STARTTLS command works on this server
[000.414]		Connection converted to SSL
		SSLVersion in use: TLSv1_3
		Cipher in use: TLS_AES_256_GCM_SHA384
		Perfect Forward Secrecy: yes
		Session Algorithm in use: Curve X25519 DHE(253 bits)
		Certificate #1 of 3 (sent by MX):
		Cert VALIDATED: ok
		Cert Hostname DOES NOT VERIFY (domain.co.uk != server.co.uk | DNS:server.co.uk)
		So email is encrypted but the host is not verified
		Not Valid Before: Jun 16 12:50:41 2024 GMT
		Not Valid After: Sep 14 12:50:40 2024 GMT
		subject: /CN=server.co.uk
		issuer: /C=US/O=Let's Encrypt/CN=R11
		Certificate #2 of 3 (sent by MX):
		Cert VALIDATED: ok
		Not Valid Before: Mar 13 00:00:00 2024 GMT
		Not Valid After: Mar 12 23:59:59 2027 GMT
		subject: /C=US/O=Let's Encrypt/CN=R11
		issuer: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
		Certificate #3 of 3 (added from CA Root Store):
		Cert VALIDATED: ok
		Not Valid Before: Jun 4 11:04:38 2015 GMT
		Not Valid After: Jun 4 11:04:38 2035 GMT
		subject: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
		issuer: /C=US/O=Internet Security Research Group/CN=ISRG Root X1
[000.522]	~~>	EHLO www12-do.checktls.com
[000.598]	<~~	250-server.co.uk 250-PIPELINING 250-SIZE 10240000 250-ETRN 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250-DSN 250 CHUNKING
[000.598]		TLS successfully started on this server
[000.598]	~~>	MAIL FROM:<[email protected]>
[000.680]	<~~	250 2.1.0 Ok
[000.681]		Sender is OK
[000.681]	~~>	QUIT
[000.756]	<~~	221 2.0.0 Bye

This only appears to happen on this domain, but we can't see what's different from any other domain. DN records are turned off and DNSSEC is turned off for this domain. There appears to be an issue with some sort of caching somewhere of an older Certificate , we have repeatedly reissued certificates from "SSL it!" for the domain.

I am much more comfortable using WHM and have other SNI domains on WHM which using the same tool -- CheckTLS.com -- come up correctly. Also other domains on the same server also come up correctly, But this one doesn't but we have nothing of difference on the DNS settings on this domain.


How do we resolve this?

Thanks

 

[Kaspar@Plesk]

Is there any particular reason you didn't include the "mail access" option in the certificate?

 

[MHC_1]

Is there any particular reason you didn't include the "mail access" option in the certificate?

No. It's the default certificate . How would I do that? I've just reissued the certificate and the checkbox for mail access is shaded out but filled in because wildcard certificate is enabled. Reissuing and that doesn't change that the mail access is somehow still not present.

Ok, further investigation finds the "You need to secure mail and domain aliases manually. They will not be secured automatically because the domain is secured with a wildcard SSL/TLS certificate." So using the wildcard certificate means that I can't certify the mail domains. How would I certify the mail domains and specific subdomains then? I don't get why these can't both be active.

THanks

 

[Kaspar@Plesk]

[...] the checkbox for mail access is shaded out but filled in because wildcard certificate is enabled. Reissuing and that doesn't change that the mail access is somehow still not present.

Enabling the wildcard certificate would only gray out the webmail checkbox. Not the "Assign the certificate to the mail domain". Is that different for you?

 

[MHC_1]

Enabling the wildcard certificate would only gray out the webmail checkbox. Not the "Assign the certificate to the mail domain". Is that different for you?

Ok reviewing that today yes, that works as you describe. I was I think cross referencing "mail domain" and "webmail" . Sorry!

Thanks for your help. This issue is resolved now