Whence comes this strange name in the email template subject? This “XYZ: Your Order…”. Responsible for this is the variable {{var order.getStoreGroupName()}}, which in the past Magento Email Templates Subject “subject” is.
The answer is hard to find, if one does not know…The name of the store is this relevant. To change this, just under “System > Configuration > Stores Management” Go there and the corresponding Store rename.
BUT ATTENTION! Take care, not that e.g.. Referring to the index.php to the store reference. Or even elsewhere.
Used in Magento versions 1.4.1.1 and 1.5.1.0 Comments? Additions? Notes? Gladly!
Addendum dated 09.04.2013
With newer versions of Magento (current 1.7.0.2) with the German locale is the o.g. Variable ersetzt. Nun ist die Variable is {{was store.getFrontendName()}}. This system is under > Configuration > General > Store Information > StoreName maintained.