After upgrading a magento website from 1.9.0.x to 188.8.131.52/3 Magento has stopped sending the order confirmation email when a customer picks anything but the icepay (iDeal) payment option. The other payment options are banktransfer, free shipping (used as an option to pay in their physical store) and cash on delivery.
The cron is configured properly and the core_email_queue table is empty, and when send from the backend it also sends out the email. I have placed some logging in the email process and it seems it never actually gets to trying to send anything even though Magento claims it has send the email.
We are also using mandrill to send email and the mandrill logs are also empty, there are no warnings/exeptions related to the email process in any of the log files either.