"Fallback" - what does it mean?

[Perfect Eye]

I'm setting up Worldpay in Actinic, and in the configuration menu it has a tick box called "Fallback"

Can anyone tell me what that means, and whether its best to tick it or leave it blank?

Many thanks

[marknc]

I think you mean "Callback".
A customer buys from your site and checks out via the WorldPay secure server. After the credit card transaction is complete, WorldPay then return the information to your website to tell you whether or not the transaction was successful.
Sometimes, a glitch in this transfer of information occurs and you can either receive incorrect or incomplete information when you download the order to Actinic. eg, an authorised transaction may return to you as PSP Pending.
If you leave the Callback box unticked you will not know that this error ocurred. If you tick it and enter your email address you will be notified if and when this happens.
In our experience it happens rarely. But we do need to know when it does and this is a useful function to have enabled.
Mark