Large numbers and months of inbox emails deleted and I couldn't stop it

I was using MS / Outlook email as normal on my Android phone and suddenly large batches of emails started disappearing. 

After each batch, a message appeared with something like "It's good to have an empty inbox", accompanied by a sort of cartoon drawing with a circle and other bits. They went away very quickly so it wasn't possible to screenshot it or remember it very well.

When I couldn't stop it, I closed the email screen and carefully checked it sometime later. Some more had disappeared, but it had now stopped and now I am receiving new emails normally but with a big gap of missing emails. All the emails in my folders still appear to be present and OK, thank goodness. 

I have been involved in computing, etc., for a long time but I am totally mystified by what happened. 

I have a current Norton 360 and did exhaustive scans, etc., but it did not find any risky items or anything else amiss. 

If anyone can offer any help it would be greatly appreciated. 

I will now also contact Microsoft to see what help they can offer to hopefully recover my deleted emails? 

I am sure you must have checked both deleted and recovery folders available on outlook.com for your signin ID on your PC. Phones do not have the recovery folder.

New versions of Outlook being installed on your phone may have played havoc with your email inbox. I would definitely contact Microsoft about it.