Installed Office 365 several days ago just for (temporarily) OL 2016.

2 email accounts: Outlook.com and a Kerio Connect (a multi platform exchange type account) installed as IMAP for our domain name.

The Kerio account is the default.

My wife came upstairs last evening and said she issued an email from the Kerio account and the email appeared in the Outlook.com sent box. I said 'no way' and looked for myself.

The email in the the Outlook.com sent box clearly said 'from' the Kerio account.

I sent a test email myself from the Kerio account (it clearly said 'sending from 'KOC' at the top) and darn if it didn't also appear in the Outlook.com sent account.

I bet a nickel no one here has had this experience or has a clue as to why!

Mark

Here's the solution:

https://support.microsoft.com/en-us/kb/2391896

One would think if MS knew of this sporadic problem since OL 2007 they would have devised a solid fix at least by OL 2016.

Mark