How to save emails sent from a different mailbox to the Sent Items of that mailbox

Here is how you can send an email as a different mailbox and then have that sent email go to the Sent Items for that mailbox and not your default Mailbox.

Compose Email

Open a new email and choose the From button to choose your other email account.

Select Other Account

Select the email address you want to send from.

Choose Option to Save Sent Item to Mailbox

Choose from the menu, Options and then the Save Sent Items to Dropdown.

Select Other Folder

Choose to save the Sent Item to Other Folder.

Select the Sent Items Folder you want

Now you can select the Mailbox you want the Sent Item to be saved in and the folder in that Mailbox.