Forum Discussion
Phantom Office 365 Mailboxes
Noticed something similar in a dev tenant yesterday.
In case it could help diagnostics:
Created new user in O365 Admin (no AAD sync in place, standalone tenant), no licenses assigned.
Bought SP Online Plan 1.
Assigned SP P1 to the new user (nothing else).
In SharePoint homepage - created new team site.
In the new team site - clicked on Group conversations.
Outlook.office.com opens.
Can send mail from here but reply-to address is (redacted):<IMCEAEX-_O=EXCHANGELABS_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=6E6F20D1C7A0465088786E6633A8F67F-username+2EBILL@eurprd05.prod.outlook.com>
Can not receive mail.
That's unsurprising. You need an Exchange Online license to be able to access the conversations in an Office 365 Group mailbox. The SP1 license is sufficient to get to the group files, but not the conversation. However, OWA should barf in a nicer manner.
- That's my point, for users with only SP1 this shouldn't create them a "pretend" email account. Posted the description as an optional aid in debugging the original issue as the result is much the same:-)
I think what happens is that the creation of the group kicks off the provisioning process to make sure that all group resources are available. Some group members might have EXO licenses, some might not. In your case, you accessed the group mailbox with a user that is not licensed to use EXO, so the attempt to send mail was rejected by the transport system because of your unlicensed status. The group mailbox and its assigned email address are perfectly valid and are required to serve people with EXO licenses...
- That is indeed the case. There is no problem for EXO users in this scenario, but it is not an acceptable outcome for SP1 users to have a default link on a team site that automatically logs them into what appears to them to be a normal Outlook mail account (from which you can send mail but not receive). Ideally the link to the group conversation should be removed for unlicensed users in my opinion, or at least display some meaningful error message.