Error message

• Unable to send e-mail. Contact the site administrator if the problem persists.
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/cymtv.com/includes/common.inc:2780) in drupal_send_headers() (line 1486 of /var/www/cymtv.com/includes/bootstrap.inc).
• Error: Call to undefined function imap_open() in support_client_fetch() (line 3584 of /var/www/cymtv.com/sites/all/modules/support/support.module).