Mailserver doesn't receive Hika system mails

-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6

Hi,
we have a strange problem with Hikashop sytem mails. All rerouted mail addresses won't receive them. If somebody registers for instance with a gmail address it works fine. But if somebody registered with an alias or rerouted mail address, they don't receive a confirmation mail.
What could be the reason for that?
Cheers
Roger

Hi,

HikaShop does not have a specific mail system, it is using the Joomla mail system to send his emails.

Regards,