缓存空间不足

异常时间：2017-01-14 11:43:12
javax.mail.MessagingException: No buffer space available (maximum connections reached?): connect;
  nested exception is:
    java.net.SocketException: No buffer space available (maximum connections reached?): connect
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:461)
    at javax.mail.Service.connect(Service.java:236)
    at javax.mail.Service.connect(Service.java:137)
    at util.MailUtil.recvImapMail(MailUtil.java:482)
    at mail.MailBusiness.receiveMail(MailBusiness.java:347)
    at mail.MailThread.run(MailThread.java:25)

解决：

重启服务。