Please make sure the email address on the email you are trying to sync is exactly the same as the one on the record you are expecting it to sync to, if there is any difference, it will not recognise it as the same or sync it to the record.
Common solutions are:
Check Synchronization Has Been Setup
In the bottom right of the taskbar (check also notifications area under '^'), right-click the RDB Sync icon and select Options.
From the Explorer Bar (left-hand side) of the Options window Click General.
Click Authentication.
From Outlook Connection Settings check that the correct Profile Name has been selected.
From the General sub-menu (left-hand side) click Synchronization.
Ensure that the desired Outlook objects (Calendar, Tasks and Emails) have been selected.
From the General sub-menu (left-hand side) Click Schedule.
If automatic synchronization is required ensure that the period under Synchronize Every is long enough to be completed (e.g. 30 minutes).
Click OK.
Check Email Options Are Correct
In the bottom right of the taskbar (check also notifications area under '^'), right-click the RDB Sync icon and select Options.
From the Explorer Bar (left-hand side) of the Options window Click Email.
Click Import Only Selected Mail Folders and select folders to sync.
📌 Note: Best practice to limit the number of folders to sync emails from. Too many folders could mean that RDB Sync does not completely go through all expected folders as it runs out of time (under automatic sync conditions) or crashes due to networking issues.
Click Age Filter from the Explorer Bar on the left-hand side.
Click Import Emails within Last and select the number of weeks RDB Sync needs to go back each time it is executed. The best practice is to keep this to a minimum.
Click Defaults from the Explorer Bar Email option on the left-hand side.
Click Import Mails Only From Recognized Contacts.
Click Non-Private.
Click Received from the Explorer Bar Email option on the left-hand side.
Click Emails folder from the Notebook Folder.
Select the appropriate Email Notebook Type.
Click Sent from the Explorer Bar Email option on the left-hand side.
Click Emails folder from the Notebook Folder.
Select the appropriate Email Notebook Type.
Click OK.
📌 Note: Best practice to limit the number of folders to sync emails from. Too many folders could mean that RDB Sync does not completely go through all expected folders as it runs out of time (under automatic sync conditions) or crashes due to networking issues.