Which encryption value ("" (empty), SSL or TLS) should I choose in the .yaml configuration file?

In the documentation, at the email configuration level, you can choose different values for encryption: “” (empty), ssl or tls.

My domain name is currently secure and has redirection rules (.htaccess, rewrite engine). So I do have https instead of http in my address bar. Everything is working well at this level.

The problem is that I don’t know what value to put in the configuration file for emails: “” (empty), ssl or tls ?

The configuration information given by my host (1and1 - Ionos) is not clear. It seems that it is possible to put ssl or tls… but I’m not sure. I don’t even know if it depends on the type of contract.

Finally, I would like to point out that currently no encryption information is entered in the configuration file… and it works perfectly (I receive emails well).

I just want to have a good configuration file, and therefore put the right encryption value.

Would you have an idea ?

Thank you in advance.

This has nothing to do with your domain.
This is all about how the emails are to be send and which type of transport layer encryption is to be used.

“Empty” is no good. That’s like the HTTP or FTP of the email webs. “Everybody” (who can read your net traffic) can plainly see and read your sent emails.
SSL is deprecated (since 2015).
TLS is the current standard.