Email Aliases and Group Mail Addresses

I have a new Mac Mini Server, and have a question moving legacy email addresses and user accounts (from a Linux server).

A user John Doe might have a legacy account name jdoe, and an email address john.doe@mycompany.com

I have implemented the same scheme with the Server App, setting the user email address as an alias in the user-creation dialog box.

With the Server App, I later created groups for mailing lists.

For some users with aliases, I will get an error message complaining about an alias address showing up in the mail list. For example, an email to a group might complain about the john.doe@mycompany.com address, but not jane.doe@mycompany.com

The error message:

<john.doe@mycompany.com> (expanded from <groupname@mycompany.com>): user unknown

When creating user accounts, I went sorta fast. Not sure if I missed some sequence thing on some accounts but not on others. To get the functionality that I am looking for, do you have suggestions on how to proceed (re-create accounts, etc.)?

As a short-term fix, I edited /etc/aliases so that groups use the account names and not alias email addresses, and things are working. Long-term, it seems like this functionality is there in the Server app, and I would like to get this functionality in place "the Apple way".

Thanks!