In order to send abandoned cart emails, the Remarkety connector needs to read the information for all current carts in the system. VirtueMart stores these carts in the users' session, and so in order to read cart information, we need access to the users' sessions.
There are several reasons why Remarkety cannot access the sessions and thus the Virtuemart carts:
Sessions must be saved to the database so that Remarkety can read them.
In Joomla: Site -> Global Configuration -> System -> Session Settings make sure that the session handler is set to 'database'
Sessions must persist long enough so Remarkety has a chance to read them before they expire.
In Joomla's global configuration, make sure that the session lifetime is longer than the longest cart followup time in your Ramarkety abandoned cart campaigns. For example, you you have a 24 hours abandoned cart campaign, make the session life time 1,500 minutes or longer, to make sure it will not be deleted before Remarkety had a chance to pick it up.
PHP suhosin extension
Your installation might have an extension called 'suhosin' which encrypts the sessions. If so,the Remarkety connector cannot read them.
From our experience, the only way to overcome this is to disable the suhosin extension. Once this extension is disabled, the sessions will not be encrypted and Remarkety connector will be able to read them and extract the cart info.
To check if your PHP has this extension, in your Joomla admin navigate to: Site -> System Information -> PHP Information and search for 'suhosin'
To remove suhosin, open a support ticket with your hosting provider or take a look here, it may help: http://www.magentodeveloperleedsuk.co.uk/disable-suhosin-on-the-server-using-php-ini-or-htaccess-files/