also nichts an den einstellungen ändern?

nicht alles ungeprüft glauben.

Sieht man bei UPC wohl anders, da wird ausdrücklich von "keine
Verbindungssicherheit" und "Passwort übertragen, unverschlüsselt" in der
FAQ-Anleitung gesprochen!

SSL/TLS vs plaintext/STARTTLS port numbers

The above is particularly problematic when combined with having to configure a port number for each protocol.

To add security to some existing protocols (e.g. IMAP, POP, etc.), it was decided to just add SSL/TLS encryption as a layer underneath the existing protocol. However, to distinguish that software should talk the SSL/TLS encrypted version of the protocol rather than the plaintext one, a different port number was used for each protocol. So you have:

    IMAP uses port 143, but SSL/TLS encrypted IMAP uses port 993.
    POP uses port 110, but SSL/TLS encrypted POP uses port 995.
    SMTP uses port 25, but SSL/TLS encrypted SMTP uses port 465.

At some point, it was decided that having 2 ports for every protocol was wasteful, and instead you should have 1 port that starts off as plaintext, but the client can upgrade the connection to an SSL/TLS encrypted one. This is what STARTTLS was created to do.

There were a few problems with this though. There was already existing software that used the alternate port numbers with pure SSL/TLS connections. Client software can be very long lived, so you can't just disable the encrypted ports until all software has been upgraded.

Mechanisms were added to each protocol to tell clients that the plaintext protocol supported upgrading to SSL/TLS (i.e. STARTTLS), and that they should not attempt to log in without doing the STARTTLS upgrade. This created two unfortunate situations:

1. Some software just ignored the "login disabled until upgraded"announcement and just tried to log in anyway, sending the username and password over plaintext. Even if the server then rejected the login, the details had already been sent over the Internet in plaintext.
2. Other software saw the "login disabled until upgraded" announcement, but then wouldn't upgrade the connection automatically, and thus reported login errors back to the user, which caused confusion about what was wrong.

Both of these problems resulted in significant compatibility issues with existing clients, and so most system administrators continued to just use plaintext connections on one port number, and encrypted connections on a separate port number.

This has now basically become the de facto standard that everyone uses. IMAP SSL/TLS encrypted over port 993 or POP SSL/TLS encrypted over port 995. Many sites (including FastMail) now disable plain IMAP (port 143) and plain POP (port 110) altogether so people must use an SSL/TLS encrypted connection. By disabling ports 143 and 110, this removes completely STARTTLS as even an option for IMAP/POP connections.

was bedeutet das für pc, handy, usw?

Das ist aber nicht der Sinn der Sache, der Sinn ist Spam etwas einzudämmen