Which Characters Can be Used in 'Member Management' Email Addresses and Validation Rules?

Which characters can be used in 'Member Management' email addresses?

By default, Kuroco validates email addresses using a specific regular expression pattern. However, you can configure it to use RFC-compliant email address validation instead.

Email Validation Regex

Kuroco uses the following regular expression pattern for email address validation with the preg_match() function:

preg_match('/^[a-zA-Z0-9.+!#$&*=?^_{|}~-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/', $email_address)

This regular expression validates email addresses with the following criteria:

• Local part (before @): Alphanumeric characters, period, percent, plus, exclamation mark, hash, ampersand, asterisk, equals, question mark, caret, underscore, pipe, tilde, and hyphen are allowed
• Domain part (after @): Alphanumeric characters, period, and hyphen are allowed, with a top-level domain of at least 2 characters required

Email Validation Function Implementation

Kuroco uses the is_email() function for email validation, which has two different validation modes depending on configuration:

Validation Modes

Default Behavior (Regular Expression Validation):
By default, Kuroco uses custom regex pattern validation with the following characteristics:

• Enforces a maximum length of 256 characters
• Allow a specifically defined character set.
• This is the standard validation method used when no special configuration is set

RFC Compliance Mode (Activated by STRICT_VALIDATE_EMAIL Constant):Release version: βversion
When you set the STRICT_VALIDATE_EMAIL constant, the validation switches to full RFC compliance:

• Provides complete RFC compliance according to official email address standards
• No custom length restrictions beyond RFC specifications
• More permissive than the default regex validation

To switch from default regex validation to RFC compliance, define:

STRICT_VALIDATE_EMAIL = 1;

This constant changes the validation behavior from custom regex pattern matching to standard RFC-compliant email validation.

info

You can configure constants like STRICT_VALIDATE_EMAIL through the Constants Management screen in your Kuroco admin panel.

Also, please be sure to convert the email address to lower case when registering it. Email addresses that use uppercase letters will all be registered in lowercase.