Our back-end system only accepts Canadian postal codes as "XXX XXX." Is there an easy way for me to customize the form field to force in that middle space so that the data is collected and exported in the required format?
In general, it's a good idea to be flexible and allow both
XXX XXX and
XXXXXX as entries, and let the system convert the latter option by inserting a space at the right position. Unlike e.g. a credit card number or a serial key, this is a short field and unlikely to cause mistypings.
(For comparison: I'm from the Netherlands; our postal codes look like
1234 AB with or without a space in the middle. It varies from person to person and from system to system which format they prefer.)
How this conversion is done is an implementation question, which is off-topic for this site. It will depend heavily on the type of system / programming language / framework you're working with.