Question did not encrypt this message - gmail

[Novadiei]

Server operating system version

AlmaLinux 8.6 (Sky Tiger)

Plesk version and microupdate number

Plesk Obsidian v18.0.47_build1800221020.08 os_RedHat el8

Hi,

I have a host with Plesk installed, that for some reason is not signing outgoing email? I went through the suggested tutorial of: https://support.plesk.com/hc/en-us/...rity-example-com-did-not-encrypt-this-message

The configuration is ok. The host is under a specific hostname, per example server3.hostname.com, i have other servers in a similar setup and this does not happend only on this one. Other domains in this plesk installation also have this issue. I can not find any differences with other plesk installations.

Plesk has a lets encrypt certificate for plesk and mail, the domain that is sending the mail has a certificate as well. The mail program is connection to the server through SSL both IMAP and SMTP.

Any ideas?

 

[ChristophRo]

What is your TLS versions and ciphers preset configured at?
Depending on the destination domain of these emails, TLS/SSL encryption may not work if configured to "modern" or even "intermediate"
And if you don't have the postfix smtp_tls_security_level set to may, it can also not fall back to sending the mail over a plain text connection and the mail remains in the queue or bounces back to sender.

 

[Novadiei]

What is your TLS versions and ciphers preset configured at?
Depending on the destination domain of these emails, TLS/SSL encryption may not work if configured to "modern" or even "intermediate"
And if you don't have the postfix smtp_tls_security_level set to may, it can also not fall back to sending the mail over a plain text connection and the mail remains in the queue or bounces back to sender.

1. TLS I have tried all of them, not one of them works.
2. No difference.
3. This is correct, the correct config is applied, it is a default Plesk installation (a new one)

I have checked against other servers that I have, I can not see any differences, that is the puzzling part.

 

[Bitpalast]

... for some reason is not signing outgoing email?

Could you please specify, what exactly your understanding of "signing" is? For example, is this question related to SSL when your mailserver connects to other mailservers? Is it related to SSL when your mail client connects to your mail server? Or is it related to DKIM or something else?