When creating a calid, keep in mind the following rules:
Calendar ID's are case sensitive. For example, JSMITH is not equivalent to jsmith. (This differs from email addresses, which are not case sensitive. For example, firstname.lastname@example.org is equivalent to JSMITH@SESTA.COM.)
A calendar ID cannot contain spaces and is limited to the following characters:
Alphabetic (a-z, A-Z) and numeric (0-9) characters (non-ASCII characters are not allowed)
Special characters: period (.), underscore (_), hyphen or dash (-), at sign (@), apostrophe ('), percent sign (%), slash (/), or exclamation point (!)
Because the user ID is part of the calid, the user ID should not contain spaces (for example, j smith). While a user with a user ID that contains a space can log into Calendar Server, the space can cause subsequent problems.
Examples of proper calendar ID's are: