When arranging a conference call using the Easy Invite feature in your calendar application, the email invite will only go out to a distribution list if you expand the list of emails first.
Depending on the email client the option varies, for Outlook click on the 'plus' icon, as below
Not expanding the distribution list first to display all attendees before sending will result in the email invites not being delivered.
Please note: The maximum number of attendees you can arrange via email invite is 200
If the number you wish to attend exceeds this then please invite manually using your shared conference ID or the same attendee invite.
For more information or if you continue to experience issues with email distribution lists then please contact our support team. T: +44 (0) 203 137 8933 E: firstname.lastname@example.org