Problem

* The gateway comes with a number of sample regular expressions (regexes) but it's not clear what they match or what format they are in.

Resolution

- The gateway uses Java-style regexes. There are online tools that will describe what the regex should be expected to match in detail. When creating a regex, you should be clear about the patterns you intend to match or not match. In particular, the email regex only matches non-accented Latin characters (a-z). If this doesn't describe the emails you expect to see used, you might wish to use a more complete Java email regex instead, which describes most allowable email addresses, but be aware of the many trade-offs in regex validation of emails.