Restored 2 day old Microsoft Exchange - lost one month of entries

I have a strange situation. On the weekend our Exchange 2010 system got fried, so I pulled out the backup from Friday 12/12/2014 and restored it.

Now when our users reconnect to their mailboxes, whether via Outlook or their phones, they don't see anything after 18/11/2014. I watched the content disappear with my own eyes. One moment it was there, the next, bam - gone. Almost a month of data is gone from their devices. Emails, appointments, etc. Everyone's outlook is running in Cached mode - I have no idea what the devices themselves do (some are iPhones, some are Android).

However: If I log into the web interface, everything is intact. I can see entries right up to when the backup was taken.

What's going on? Will the users Outlooks eventually sort themselves out? New content (inbound emails) are appearing correctly in the mailbox.

Right now I've just advised our users to get onto their webmail.

Patience is a virtue. It took a very long time, but eventually all the items that went missing re-appeared. I suspect that a part of the reason it took so long was because the way Veeam Backup and Recovery works, is you can boot the VM directly off your disk-based backup storage, and then you can do a storage migration off the backup device to your proper storage. This means that you can do a restore of your VM almost instantly.

However, during this stage, depending on your backup hardware, the server can be excruciatingly slow - especially during the storage migration. That doesn't explain why they went away, but it explains why they took so long to come back.