All outgoing emails are also being sent to OneNote.

[BigHamps]

It's driving me nuts.

There are no rules in Outlook, where else can I look for a solution?

[#2]

HI, maybe there is a mail flow rule ??

[#3]

That looks like some add-in interfering, check for those or simply run Outlook in safe mode ('Outlook /safe' in the run box or hold the CTRL key when launching it).

[#4]

I asked my IT guy who manages my 365 account and he says there are no rules.

If I log in on my Mac, there are no local rules or exchange rules.

@JaksaSkelin 

[#5]

@Vasil Michev  It's not my desktop version of Outlook. If I send it from Outlook on my phone, it still ends up in OneNote.