Yesterday I added in 4 more email accounts and started to have this error : 0x800CCC0F
So I do some testing myself and here are the result:
If I click send/receive (which is all 6 accounts) I will get the error.
If I remove 2 accounts and only have 4 email accounts, I will not error any error with the send/receive all function, the problem seems to come as long as I have 5 email accounts and above.
If I click one by one account under send/receive, I will not get any error with all 6 email accounts. (which means the account setting is correct).