I am having troubles sending email with an attachment through rouncube. I did confirm that I can send attachments via IMAP using the Thunderbird email client. I have set PHP memory limit to 32M and the email attachment limit to 12M in roundcube. When I try to send a 2M attachment I get the following 2 lines in the error log:

[21-Jan-2010 07:00:27] PHP Warning:  sort() expects parameter 1 to be array, boolean given in /var/www/roundcube/program/include/rcube_imap.php on line 1118
[21-Jan-2010 07:02:11] PHP Fatal error:  Allowed memory size of 33554432 bytes exhausted (tried to allocate 6952037 bytes) in /var/www/roundcube/program/lib/Net/SMTP.php on line 887

It looks like PHP is already exhausting the 32M, but I have no idea why?