zimbra错误：A network service error has occurred : timestamp check failed.

zimbra的ssl过期，安装后默认是1年有效期。

过期后解决方法：

原文：http://www.unixsurgeon.com/kb/a-network-service-error-has-occurred-timestamp-check-failed.html

1. Begin by generating a new Certificate Authority (CA).

# ./zmcertmgr createca -new

2. Then generate a certificate signed by the CA that expires in 365 days.

# ./zmcertmgr createcrt -new -days 365

3. Next deploy the certificate.

# ./zmcertmgr deploycrt self

4. Next deploy the CA.

# ./zmcertmgr deployca

5. To finish, verify the certificate was deployed to all the services.

# ./zmcertmgr viewdeployedcrt

Then restart the zimbra mail server once again,now your all the users can access their webmail account.