Users with additional email addresses not create when Add mail attribute to LDAP users/Yes using `mail` and `mailAlternateAddress` is selected in advanced virtualmin options

SYSTEM INFORMATION
OS type and version Debian 12
Webmin version 2.101
Virtualmin version 7.7

With the following option selected, new users cannot be added to domains if an additional email address is supplied.

Virtualmin > Virtualmin Configuration > Advanced options > Add mail attribute to LDAP users > Yes using mail and mailAlternateAddress

When adding a new user with additional email address(es), this error is returned and no user is created.

Failed to save user : Failed to add user to LDAP database : mailAlternateAddress: attribute type undefined

When adding a new user without additional email address(es), the user is created and the LDAP object for the user contains a populated mail attribute.

After changing the configuration above to

… > Add mail attribute to LDAP users > Yes using only mail attribute

and adding a new user with additional email address(es), the user is created and the LDAP object contains a mail attribute for the ‘primary’ email address and for each additional email address.

Also, an object is created under dc=Virtual,dc=domain,dc=tld for each email address*.

As far as I could find, mailAlternateAddress is an attribute of the MailGroup object class, but I cannot find a schema that actually includes that class. It isn’t defined in any of the schema/ldif under /etc/ldap/schema.

I found references to MailGroup here: LDAPWiki: MailGroup; and reference to mailAlternateAddress here: LDAP Attribute Reference. The latter links mailAlternateAddress to RFC 2256, but RFC 2256 (X.500) doesn’t mention mailAlternateAddress and neither do the RFCs that supercede RFC 2256.

I guess if anyone knows where that attribute is defined, that’d be useful and I can add it into my setup. In the meantime, perhaps additional text on the tooltip for the option above could warn about a potential problem.

* I was expecting to see these objects created under dc=Aliases,dc=domain,dc=tld, but I think that just shows a lack of understanding on my part.