[18:22:53 ERROR]: Could not load 'plugins\cubenex.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: javax/mail/MessagingException
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:133) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:327) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:248) [spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.craftbukkit.v1_12_R1.CraftServer.loadPlugins(CraftServer.java:306) [spigot.jar:git-Spigot-3d850ec-809c399]
        at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:205) [spigot.jar:git-Spigot-3d850ec-809c399]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:545) [spigot.jar:git-Spigot-3d850ec-809c399]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_151]
Caused by: java.lang.NoClassDefFoundError: javax/mail/MessagingException
        at allgemein.Main.<clinit>(Main.java:94) ~[?:?]
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_151]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        ... 6 more
Caused by: java.lang.ClassNotFoundException: javax.mail.MessagingException
        at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_151]
        at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_151]
        at allgemein.Main.<clinit>(Main.java:94) ~[?:?]
        at java.lang.Class.forName0(Native Method) ~[?:1.8.0_151]
        at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_151]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:129) ~[spigot.jar:git-Spigot-3d850ec-809c399]
        ... 6 more