u/i-c-hill

I’m having troubles backing up a single user’s Exchange Online mailbox (they have an O365 Business Premium licence). The error is not consistent. Sometimes backup works:

https://preview.redd.it/dq59oryvor8h1.png?width=602&format=png&auto=webp&s=0f06dac5f78d639c53b17330722c25a57a5ff48f

And sometimes it doesn’t:

https://preview.redd.it/iwilnuyvor8h1.png?width=602&format=png&auto=webp&s=8d7e2bd9b63c2b3aeeb7dda9595f044815e9a9c6

So I extracted the single user to a separate backup job to test it. Still failing:

https://preview.redd.it/b32httyvor8h1.png?width=602&format=png&auto=webp&s=0ac0b100a2acadcf3c9d5c47df1913a5ea1c168f

I checked the users licensing:

https://preview.redd.it/o0feksyvor8h1.png?width=274&format=png&auto=webp&s=b10475aeadae283d4d39092bf00abbfdefcd4a9b

https://preview.redd.it/6fsputyvor8h1.png?width=404&format=png&auto=webp&s=37eba50e5e3c92ef80b055a0d2021318b8e3ee2f

https://preview.redd.it/pyksmtyvor8h1.png?width=440&format=png&auto=webp&s=1b82916a7a3abd29c93312e9677526482e5a2f73

I can send email to them and they can send email to me.

I checked the Entra app permissions and I think they are correct. I recreated the certificate-based connection between the PC doing the backups and the Entra app portal. Everything still works fine for other users - but not for “Maxine”.

I also tried upgrading from Veeam Backup for O365 v8.3 to v8.4, but no change.

The other users’ mailboxes are being backed up fine. It’s just this single user, the most recently created user in the tenant, that has issues.

Our backup is on the end of a 100Mb ISP internet connection. It *almost* looks like a load-dependent error, but if that were the case, then other mailboxes would also be impacted - but they're not. Any suggestions for ways to debug this issue?

The several not-for-profits I support have tiny fleets of Windows PC. This one consists of 4 Entra-joined and 2 Entra-registered PCs. All are managed by Intune. All have device config profiles assigned to turning on both device telemetry and device health monitoring.

However, only the Entra-joined PCs report Secure Boot status. The Entra-registered PCs (PBC015 and PBC022) report “Unknown” status.  Also, they show Intune is not getting the most basic information about OS version etc.

Device name	OS version	Secure Boot enabled	Device model	Certificate status	Secure Boot trust setting	Confidence level	Data last reported	Alerts
PBC003	10.0.26200.8390	Yes	Inspiron 5593	Not up to date	Microsoft and non-Microsoft	Under Observation - More Data Needed	19/05/2026, 05:45 am	0
PBC015		Unknown		Unknown				1
PBC018	10.0.26200.8390	Yes	Latitude 5450	Not up to date	Microsoft and non-Microsoft	Under Observation - More Data Needed	27/05/2026, 12:33 am	0
PBC019	10.0.26200.8390	Yes	Latitude 5450	Not up to date	Microsoft and non-Microsoft	Under Observation - More Data Needed	26/05/2026, 10:24 am	0
PBC020	10.0.26200.8390	Yes	Latitude 5450	Up to date	Microsoft and non-Microsoft	No Data Observed - Action Required	20/05/2026, 12:18 pm	0
PBC022		Unknown		Unknown				1

Intune shows all the devices as Intune registered and managed and the account I used to register PBC015 and PBC022 has an O365 Business Premium licence.:

Device name	Managed by	Ownership	Compliance	OS version	Device state	Primary user UPN	Intune registered	Azure AD registered
PBC003	Intune	Corporate	Compliant	10.0.26200.8390	Managed		Registered	TRUE
PBC015	Intune	Corporate	Compliant	10.0.26200.8457	Managed	<deleted>	Registered	TRUE
PBC018	Intune	Corporate	Compliant	10.0.26200.8390	Managed		Registered	TRUE
PBC019	Intune	Corporate	Compliant	10.0.26200.8390	Managed		Registered	TRUE
PBC020	Intune	Corporate	Compliant	10.0.26200.8390	Managed		Registered	TRUE
PBC022	Intune	Corporate	Compliant	10.0.26200.8457	Managed	<deleted>	Registered	Unknown

I've noticed the same behaviour on another of my NFP fleets today... so it's not just these two devices - there's something consistently problematic about Entra-registered devices both fleets.

I'm not sure if it's because we license the users for Office 365 Business Premium rather than one of the "E*" licences? Any other suggestions where I should look? TIA.