tlsv1 alert unknown ca: SSL alert number 48

Wed Jun 15 20:26:38 UTC 2016

Hi,

I have set up a mail server with postfix+dovecot 2.2.13 on my raspberry pi
running Raspbian Jassie OS.

Now I would like to add an on-line e-mail client like Squirrelmail or
Roundcube. I was able to start up these two clients but when I try to login
I get this error message in the dovecot log:

tlsv1 alert unknown ca: SSL alert number 48

But I have inserted the self-signed certificate and key in
/etc/dovecot/conf.d/10-master.conf

Moreover, I can send and receive e-mails from/to my server, and I can login
successfully to dovecot IMAP with Thunderbird.

Can somebody give me a clue on how to solve this problem? Any help would me much
appreciated.

Regards,
Maurizio