[root@localhost ~]# yum install php-imap
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.nforce.com
 * extras: mirror.serverius.net
 * remi: remi.mirrors.cu.be
 * remi-php56: remi.mirrors.cu.be
 * remi-safe: remi.mirrors.cu.be
 * updates: mirror.sitbv.nl
base                                                     | 3.7 kB     00:00
epel                                                     | 4.7 kB     00:00
extras                                                   | 3.4 kB     00:00
remi                                                     | 3.0 kB     00:00
remi-php56                                               | 3.0 kB     00:00
remi-safe                                                | 3.0 kB     00:00
updates                                                  | 3.4 kB     00:00
Setting up Install Process
No package php-imap available.
Error: Nothing to do

yum search php | grep imap