I am unable to set a default signature for sending as a shared mailbox in Outlook. The shared mailbox is automatically added by Outlook after being created in the Office 365 Admin center. I can send as the shared mailbox by selecting the mailbox in the "From:" field in an email draft. However, the email still contains the signature for my personal email. I unable to set an email signature under File -> Options -> Mail -> Signatures.... Under the "E-mail account:" drop-down selector there is no option for the shared mailbox. Only my personal email is selectable.
I also tried adding the shared mailbox as an e-mail account with my personal credentials but I get an error when clicking the account on the left-hand menu: "The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed."
Please help. I really need a different signature for the shared mailbox and copying and pasting for each email is a hassle.
