cPanel & WHM version 58 will reach End of Life in 1 month, at the end of July, 2017. cPanel & WHM versions 56 and 60 will also reach End of Life at the end of October, 2017.
In accordance with our EOL policy (https://go.cpanel.com/longtermsupport), when a version of cPanel & WHM reaches End of Life it will no longer be supported by cPanel, except when upgrading to a supported version. The software will continue functioning on servers where it is already installed. However, no further updates, including security and feature updates, will be provided once it reaches End of Life.
We recommend that all customers migrate any existing installations of cPanel & WHM version 56, 58, and 60 to the most recent version of cPanel & WHM 64, which you can read about on https://releases.cpanel.com.
If your server setup complicates the process of migrating to a newer version of cPanel & WHM (an upgrade blocker list is available at https://go.cpanel.com/blockers), then cPanel is here to help. Simply open a support ticket at https://tickets.cpanel.net/submit so that our knowledgeable support team can provide recommendations, migration assistance, and more.
For the PGP-signed message, see ۵۸ EOL 1 Month-signed.