You can view a list of all the messages that you have sent or received through the events management system by going to your 'My Details' page under the 'People' section, and then clicking 'Messages' from the 'Tools' dropdown menu at the top-right of the page.
You can view all of the messages sent for a particular event in the same way; by clicking the 'Tools' dropdown menu at the top-right of the event's details page.
Viewing a message which was sent will be shown in the following way;
Messages which failed to get delivered are shown as follows, with a the name of the recipient which failed to receive it shown in red.
More details on recipients can be shown by clicking ‘View details’ (above);
The above popup will show the email address or phone number used when this message was sent, along with the details of when it was sent and the delivery-status for each person.
Note that whilst it may show ‘Delivered’, this may not completely take into account spam filtering, any rules the recipient may have setup to automatically discard or archive messages, etc.
For this reason, the delivery status should only be treated as a general indication that it didn’t encounter any major problems when getting sent (eg. the email didn’t get rejected by the recipients email server).