Currently the id field only can contain alphanumerics and '-', '_', ':', or '~'.

This character set would need to be extended to incorporate items such as email addresses as part of an id.

As a workaround, content that cannot be stored using the currently available character set, can be converted to base62 (https://en.wikipedia.org/wiki/Base62).

Base 62 characters are: capital letters A-Z, the lower case letters a-z and the numbers 0–9. Which all fit in the current id field's character set.