Add mail attribute to LDAP users?
When storing Virtualmin users in LDAP, this setting allows you to have their email addresses added to the LDAP database as well. This is useful if your mail server or spam filter use the same database to deliver email.

The available options are :

When this is set to Yes, Webmin will add LDAP mail attributes to each user it creates or modifies for their primary and additional email addresses. This is useful if you are using the same LDAP database with a mail server which uses that attribute to figure out where to deliver email.