Code:
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.GeneratedConstructorAccessor181.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1129)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:358)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2498)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2343)
    ... 50 more
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at java.net.Socket.<init>(Socket.java:434)
    at java.net.Socket.<init>(Socket.java:244)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:308)
    ... 52 more
2017-01-30 16:57:27,852 INFO  [ImapSSLServer-36572] [] cache - initializing folder and tag caches for mailbox 11
2017-01-30 16:57:31,855 WARN  [ImapSSLServer-36572] [] imap - Skipping error while trying to serialize during close (Drafts)
com.zimbra.common.service.ServiceException: system failure: getting database connection
ExceptionId:ImapSSLServer-36572:1485791851855:66c37600ebd3c239
Code:service.FAILURE
    at com.zimbra.common.service.ServiceException.FAILURE(ServiceException.java:260)
    at com.zimbra.cs.db.DbPool.getConnection(DbPool.java:360)
    at com.zimbra.cs.mailbox.Mailbox$MailboxChange.getConnection(Mailbox.java:421)
    at com.zimbra.cs.mailbox.Mailbox.getOperationConnection(Mailbox.java:1607)
    at com.zimbra.cs.db.DbMailItem.getFoldersAndTags(DbMailItem.java:2098)
    at com.zimbra.cs.mailbox.Mailbox.loadFoldersAndTags(Mailbox.java:2201)
    at com.zimbra.cs.mailbox.Mailbox.beginTransaction(Mailbox.java:1771)
    at com.zimbra.cs.mailbox.Mailbox.beginReadTransaction(Mailbox.java:1686)
    at com.zimbra.cs.mailbox.Mailbox.getItemById(Mailbox.java:2773)
    at com.zimbra.cs.mailbox.Mailbox.getItemById(Mailbox.java:2765)
    at com.zimbra.cs.mailbox.Mailbox.getFolderById(Mailbox.java:3903)
    at com.zimbra.cs.imap.ImapSessionManager.cacheKey(ImapSessionManager.java:607)
    at com.zimbra.cs.imap.ImapSession.unload(ImapSession.java:320)
    at com.zimbra.cs.imap.ImapSessionManager.closeFolder(ImapSessionManager.java:540)
    at com.zimbra.cs.imap.ImapHandler.unsetSelectedFolder(ImapHandler.java:1007)
    at com.zimbra.cs.imap.NioImapHandler.connectionClosed(NioImapHandler.java:166)
    at com.zimbra.cs.server.NioHandlerDispatcher.sessionClosed(NioHandlerDispatcher.java:79)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.sessionClosed(DefaultIoFilterChain.java:665)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:395)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:46)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:781)
    at org.apache.mina.filter.codec.ProtocolCodecFilter.sessionClosed(ProtocolCodecFilter.java:387)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:395)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:46)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:781)
    at org.apache.mina.core.filterchain.IoFilterAdapter.sessionClosed(IoFilterAdapter.java:95)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:395)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:46)
    at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:781)
    at org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:110)
    at org.apache.mina.core.session.IoEvent.run(IoEvent.java:63)
    at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTask(OrderedThreadPoolExecutor.java:780)
    at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTasks(OrderedThreadPoolExecutor.java:772)
    at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.run(OrderedThreadPoolExecutor.java:714)
    at java.lang.Thread.run(Thread.java:745)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
    at sun.reflect.GeneratedConstructorAccessor4707.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.Util.getInstance(Util.java:386)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1015)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:920)
    at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2404)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2325)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.GeneratedConstructorAccessor212.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:347)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:208)
    at org.apache.commons.dbcp.DriverManagerConnectionFactory.createConnection(DriverManagerConnectionFactory.java:78)
    at com.zimbra.cs.db.ZimbraConnectionFactory.createConnection(ZimbraConnectionFactory.java:67)
    at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
    at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1188)
    at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
    at com.zimbra.cs.db.DbPool.getConnection(DbPool.java:341)
    ... 33 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure...