Dear Maintainer,

With Debian Buster akonadi does not work anymore with aruba imap server, goes
in a loop "idle/connection established" without downloading anything.
In .xsession-errors file there are infinite occurrences of :

org.kde.pim.kimap: Connection to server lost 9
org.kde.pim.imapresource: Session login cancelled

It works only without encryption, if I set SSL/TLS port 993 plain  enter in
loop and if I delete account via Kmail a window asking for the imap password
is shown for a fraction of a second, when I have created the account I entered
the correct password and allowed its saving in the wallet.

My guess is that it is caused by the default configuration of OpenSSL 1.1,
which requires TLS 1.2 iirc. If that aruba imap server is using old software
that doesn't support that version, then it won't be able to connect.

I ran into a seemingly similar situation when OpenSSL 1.1 entered Sid, but I
can't remember if/where I wrote things down wrt this and/or reported it.
But you can change the config of OpenSSL to allow lower TLS versions to work.
Better would be to urge that mail provider to upgrade their mail software as
TLS < 1.2 really isn't secure.

Hopefully this gives you enough hints to search for the actual solution.

Changing back the defaults in /etc/ssl/openssl.cnf to previous system wide
defaults can be done using:
   MinProtocol = None
   CipherString = DEFAULT
It's recommended that you contact the remote site in case the defaults cause
problems.