Global Administrator as Shared Mailbox

[sramkumars]

I am new to Microsoft 365. Have recently subscribed to Microsoft 365 Business Standard. The global administrator account does not have license attached to it. But we want to add a shared mailbox to the global administrator. When we do, we get the following error

Error executing request. The proxy address "SMTP:<email address removed for privacy reasons>" is already being used by the proxy addresses or LegacyExchangeDN. Please choose another proxy address.

Is this possible at all, if yes, how to go about it.

Thanks,

Ramkumar.

[#2]

You should be able to.....but I'd very strongly recommend against it. Because you don't need a license, is there an issue with creating a new shared mailbox without GA permissions? Email is the largest attack vector for compromise, so you are inviting trouble by having a GA account with a mailbox. Generally your GA accounts should only ever be used when you need to perform some admin task that requires GA privileges, otherwise you should be using standard user accounts.

From the error above, it looks like the SMTP address you are trying to use is already in use by another object.

[#3 · Accepted solution]

Thanks for the recommendation. We will implement it. But I got around to make it working by assigning a license to the global administrator which made the account available in the list of mailboxes where I changed it to a shared mailbox. Then I removed the license from the global administrator.