To get these functions to work, you have to compile PHP with --with-imap[=DIR], where DIR is the c-client install prefix. From our example above, you would use --with-imap=/usr/local/imap-2000b. This location depends on where you created this directory according to the description above. Windows users may include the php_imap.dll DLL in php.ini.
Note: Depending on how the c-client was configured, you might also need to add --with-imap-ssl=/path/to/openssl/ and/or --with-kerberos=/path/to/kerberos to the PHP configure line.
The IMAP extension is not thread-safe; it should not be used with ZTS builds.