SMTP connection not possible

[mulder77]

I have roundcubemail on my system for years. Right now, it's a Fedora 25 package, version 1.2.5.
Since some time (upgrade to whatever version, can't remember as I am troubleshooting just now) I am not able to send Emails via my provider anymore.

errors.log just tells me:

[07-Sep-2017 13:21:55 +0200]: <ggjr0okb> SMTP Error: Connection failed: Failed to connect socket: php_network_getaddresses: getaddrinfo failed: Name or service not known in /usr/share/roundcubemail/program/lib/Roundcube/rcube.php on line 1648 (POST /mail/?_task=mail&_unlock=loading1504783315740&_lang=en_US&_framed=1&_action=send)

But a simple telnet test is successful:

[root@homeserver html]# telnet mail.gmx.net 587
Trying 212.227.17.190...
Connected to mail.gmx.net.
Escape character is '^]'.
220 gmx.com (mrgmx002) Nemesis ESMTP Service ready

I set $config['smtp_debug'] = true, but I don't find any other useful information.

Any hint?

[SKaero]

Do you have the $config['smtp_server'] set in the config.inc.php?

[mulder77]

Yes, I tried multiple variants:

$config['smtp_server'] = 'mail.gmx.net';
$config['smtp_server'] = 'tls://mail.gmx.net&#039;;

With adjusted port numbers.

The error message remains the same.

[mulder77]

OK, very confusing messages, but I got it resolved now.
I needed to disable peer verification in the SSL options. Nothing to do with name resolution etc.