The LastLogonTime property in Mailbox mapping used for Exchange Online (0365) connector is marked as an obsolete attribute in Sync Editor
However this data maybe required to calculate number of days that users have been accessing their mailbox in order to perform user disablement.
In order to implement some revision optimization, Development has divided the mappings for "Mailbox" schema class into three parts:
3. Calendar Processing (User/Shared)/(Resource)
The Mailbox mapping allows the use of a revision filter to reduce the amount of touched objects during a sync. However, this revision filter will lead to the issue that not all mailboxes will be imported during synchronization and hence this will cause "LastLogonTime" to be not accurate for all objects.
As such, Development has marked LastLogonTime property as obsolete in the Mailbox mapping.
Development has made revision optimization available for "Mailbox", but not for "MailboxStatistics" and "Calendar Processing".
As such Development has moved LastLogonTime to be part of the MailboxStatistics mapping.
When a sync project is created, the 3 mappings (e.g. Mailbox, MailboxStatistic and Calendar Processing) are already configured.
MailboxStatistics will import information from ALL mailboxes without revision optimization and hence LastLogonTime will be correct for all mailboxes.