Here's a trick that your manager may find helpful. Instead of asking if a note was sent, they’ll be able to find it in their own Sent Items folder.
When messages and meeting requests are sent by a delegate, on behalf of a manager, a copy of each item is saved in the delegate's Sent Items folder; this behavior is by design.
To save sent items to the manager's Sent Items folder and not the delegate's Sent Items folder, the delegate must be logged on as the manager. This may not be acceptable because of privacy or security concerns. By design, items that are sent by a delegate cannot appear in someone else's Sent Items folder.
A solution is for the manager to grant permissions to their Sent Items folder to the delegate. The delegate can then move or copy the items from their own Sent Items folder to the manager's Sent Items folder after they open the manager's mailbox as an additional mailbox. To do this:
In the Folder List, right-click the Sent Items folder, and then click Properties.
On the Permissions tab, click Add.
Click to select the delegate from the address list, click Add, and then click OK.
Click to select the newly added name, and then click to select the appropriate permission level. Note that the Non Editing Author option is the minimum permission to set.
Click Apply, and then click OK. Repeat the previous steps for the Outlook Today root level folder.
The delegate can now copy or move items to the manager's Sent Items folder.