Outlook - signing or encrypting email for a shared mailbox

Issue:

Is it possible to set up email certificates to sign/encrypt email from a shared mailbox?  If so how- is there a resource you can point out?

Resolution:

There is no certificate needed to encrypt emails. 

Here is an article to setup the new Office 365 Message Encryption: https://docs.microsoft.com/en-us/microsoft-365/compliance/set-up-new-message-encryption-capabilities

You should be able to have an encrypt button when composing an email.

am checking if the digital signature can also be applied on a shared mailbox. For now, here are some support article for starters;

Secure Message using a digital signature

https://docs.microsoft.com/en-us/previous-versions/office/office-2007-resource-kit/cc545901(v=office.12)?redirectedfrom=MSDN

The sign button is for S/MIME which is a certificate-based encryption solution that allows you to both encrypt and digitally sign a message. If you want to have an S/MIME certificate, you can acquire from a third-party certificate provider.

This articles may help:

https://docs.microsoft.com/en-us/microsoft-365/compliance/email-encryption

https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/s-mime-for-message-signing-and-encryption

https://techcommunity.microsoft.com/t5/exchange-team-blog/how-to-configure-s-mime-in-office-365/ba-p/584516

Yes, S/MIME encryption can work with shared mailboxes if you have a certificate for it. Here is a supporting article: https://social.technet.microsoft.com/Forums/lync/en-US/225bd299-2d1d-4878-b172-cbab2cf29641/email-encryption-with-shared-mailboxes?forum=exchangesvrsecuremessaging

Yes, signed and encrypted emails can be sent to a distribution list.