What is this?
Send email from a different email address in Outlook on the Web (Webmail)
If you already have access to other NSCC email accounts, you can select which account to send the message "From".
Note: You must already have been given permissions from Digital Innovation & Technology Services to that account before you can send 'from' it.
Instructions
In the compose window, select ... then click 'Show From' to add the From line.
Now, click 'From' and then "Other email address".
That will clear the From field, which you can then use as a search box, to choose from the address book which address you want to use to send this email.
Do not type in the email address, but instead find it in the address book by searching for it by name and clicking on it.
That will then enter in the account name that you wish to send the message from.
You can now send your message and it will come from the NSCC account that you chose.
You will find that the message will likely be in your own 'Sent Items' folder.
You may drag and drop that sent message to the other mailboxes 'Sent Items' folder if you wish.
https://support.office.com/en-us/article/send-email-from-a-different-address-in-outlook-com-ccba89cb-141c-4a36-8c56-6d16a8556d2e#blml_beta