At times you will encounter an error with your roundcube system with bouncing emails caused by limitations in the mail system. If you get this error: Message size exceeds fixed limit
Chances are your message_size_limit is not set to be as flexible with your current configuration for roundcube to fix this do the following:
1. Edit the file which roundcube reads to assign the global variables /var/www/html/roundcube/.htaccess file and change the following configurations to this one.
php_value upload_max_filesize 32M
php_value post_max_size 32M
2. Check your postfix mailer configuration by issuing the command:
postconf -d |grep message_size_limit
If you did not get a value you need to fix this.
3. To fix the limit issue the command.
postconf -e 'message_size_limit = 104857600'
4. To fix the 'mailbox_size_limit' issue you need to add this using the command:
postconf -e 'mailbox_size_limit = 0'
5. Reload postfix for the changes to apply.