Outlook App on phone : distribution lists and distribution groups

A client uses distribution lists (DLs, aka Outlook Contact Groups) to send mailshots Bcc: to external contacts who are members of their club. There are 21 distribution lists, each with typically 300 addressees; some members are in more than one list. They update the lists and add or remove lists using Windows Outlook. A few of the lists are nested, with several child lists  being mailable from a parent list as well as individually.

All fine. Client happy.

They now wish to mailshot from phones as well as from Windows desktop. But Outlook Android and iOS apps don’t support DLs*, whether created on the phone or synched from Exchange.  They find Outlook on the Web clunky to use with a phone screen. And the eventual solution must be manageable from Outlook and not need the Exchange Admin Centre (EAC) or Powershell.

They were advised (in Microsoft documentation I think) to switch to ‘Microsoft 365 Groups’ which ARE supported by the Outlook app.   

But Microsoft 365 Groups themselves – with their own Sharepoint site and group calendar as well as mail – are clearly for team-working and collaboration, and managing 21 of them just to distribute mail is NOT the most elegant solution and don't resemble DLs at all. And Microsoft 365 Groups cannot apparently be nested. 

MSFT has made the wrong assumption that a DL has been superseded by a Group – that a Group contains everything a DL does and more.  And that is the problem: Groups with or without Sharepoint libraries and Calendars are clearly designed for Teams. But ‘Traditional’ DLs  are also used for mailshots to customers, suppliers and so on. Does anyone want their customers to receive an introductory email saying  “Welcome to the XYZ Group…use the group to share messages and files, and to coordinate group events” ? And ‘traditional’ DLs are maintained via Windows Outlook (or Outlook on the web) by clerical staff who should not (and do not want to) be exposed to the fearsome technicalities of EAC or Microsoft 365 AC.   

Distribution groups (NB not DLs!) sound a more promising solution, but there is no obvious way to create one in Windows Outlook: Groups Yes, but Distribution Groups No.

If a  Distribution Group is created in EAC, it is then necessary to go via Delivery Management to restrict the specified sender. To resemble sending Bcc: to a DL, there needs to be one nominated sender, and the recipient must be able to reply to the sender but not to see anyone else to whom the email has been distributed (and hence not be able to reply to them).

If any of this functionality is available with a Distribution Groups, perhaps someone can enlighten me.  

My client is now seriously testing WhatsApp, on the basis that even though broadcast lists (=Bcc DLs) are only supported on a single phone, this is an improvement on the Outlook app that doesn’t support them at all. (WhatsApp Groups, =Cc: DLs, are synched over up to 4 devices, including Windows PCs)

Since there seems to be nothing relevant in the MSFT Roadmap for the mobile app, suggestions please?

* if this is a restriction of EAS, MSFT seems to have been forgotten that much – perhaps most – phone use is now on WiFi-enabled broadband where the bandwidth and latency constraints should not be a problem.