As many people know, various email clients allow users to create "Contact Groups". These groups are generally made up of people from within an organization that are frequently emailed together, as a group. Contact Groups are especially popular within Microsoft Outlook, but they can be created in virtually any email client.
The nice thing about Contact Groups is that they'll generally sync across devices and email clients. What's NOT so nice, however, is that in order for them to sync across devices and email clients, those devices and clients need to be set up using the same protocol that was used to originally create the Contact Group.
For example, if you set up a Contact Group in Microsoft Outlook, and Outlook is syncing using MAPI, you can only sync that Contact Group to other MAPI clients. If you're using eM Client that syncs contacts using cardDAV, the Contact Group won't sync. The reverse is true as well: If you create a Contact Group in a client synced via cardDAV, it won't sync to a client that using MAPI.
The reason for this is simple, though frustrating: each protocol has its own set of properties that are used when a Contact Group is created, and these properties don't translate from protocol-to-protocol. Therefore, the limitation lays at the protocol level, not at the SmarterMail level. You'll have this issue regardless of the mail server software you're using.
Therefore, while Contact Groups can be very useful, some care should be taken when creating them. You'll need to ask if they need to sync to your phone, or to your email client(s) on other devices. If so, then maybe using a Contact Group isn't the best solution. Perhaps an Alias is a better choice as that can be used on any device or even using a webmail client. It's all up to how and where you're going to interact with it.