mail

Internet mail addresses in Mailbox form, as described in RFC 2821 .

The server stores mail addresses as UTF-8 directory strings, and thus is more permissive than the RFC. The server does not ensure that mail addresses conform to RFC 2821. If other mail applications require ASCII mail addresses, you must make sure all applications that update this attribute respect that requirement.

Be aware that matching is case-insensitive: (mail=bjensen@example.com) matches BJENSEN@example.com