Messages sent via the communicate panel work OK and messages are delivered successfully.
But if an address is entered in the cc or bcc field then we get PHP error messages and the mail isn't delivered.
"For security reasons, extra headers for the mail() functionhave been disabled, please contact support for more information. Filename: libraries/Email.php Line Number: 1537"
"Cannot modify header information - headers already sent by (output started at /path/etc/etc/system/codeigniter/system/core/Exceptions.php:170) Filename: core/Common.php Line Number: 412"
Anyone got any ideas what to try?