Message not delivered to Outlook, but visible on webmail server

[rfc]

I am having intermittent problems with some emails only not being
delivered. I knew a client had sent something and it never arrived.
I used web-mail to look at the server and there it was. I tried
forwarding this to myself, and it still didn't arrive; I tried again
to a different account, no difference. An odd thing is that Goggle
desktop CAN see them but it says they have been moved or deleted...

This has happened several times now.

I have 2 computers and the problem affects both of them. The mail WAS
delivered to my smartphone.

I'd love to know what is causing them not to be delivered and how to
fix it. It is as if Outlook has somehow flagged this as delivered but
not done so.

 

[rfc]

It seems that the Rules are auto-deleting them when they arrive...