I don't use the plugin, please clarify what you mean. Do you want to say that the option webmail_link= redefined in directadmin.conf does not change anything in the plugin? Or the link gets changed to whatever you set, but image is still the same?
John was able to solve the issue very quickly. In PHP 5.6 SSL certificates are now validated. I needed to change from the default of "localhost" to the FQDN of the server.It looks like the plugin doesn't work with PHP 5.6. I tested on PHP 5.5.38 and the login page works, on PHP 5.6.24 and PHP 5.6.25 the login doesn't work. This is running the latest 1.5 version of the script. Anyone else have this working with PHP 5.6?
In debug I see the following error:
InternalText::load(authentication): reading in ./data/skins/enhanced/lang/en/internal/authentication.txt
ConfigFile::ensureRoom: param=16 size=64
Program Location: Request::readAndProcess(*skt, 0:0:0:0:0:0:0:1, 0:0:0:0:0:0:0:1) : start
Program Location: Request::readAndProcess(*skt, 0:0:0:0:0:0:0:1, 0:0:0:0:0:0:0:1) : first line received
Cannot find first space after where GET or POST should be
Program Location: Request::readAndProcess(*skt, 0:0:0:0:0:0:0:1, 0:0:0:0:0:0:0:1) : no space after GET/POST
Program Location: Sockets::goodbye(): start
Sockets::shutdown_ssl(SSL *ssl): start
Sockets::shutdown_ssl(SSL *ssl): finished
Program Location: Sockets::goodbye(): finished
[root@server /usr/local/directadmin]# ./directadmin oCompiled on 'CentOS 6.0 64-Bit' Compile time: Feb 27 2017 at 16:25:33 Compiled with IPv6
cd /usr/local/directadmin/plugins/email_level wget https://www.directadmin.com/email_level-1.7.tar.gz tar xvzf email_level-1.7.tar.gz