I have Outlook 2016 through office 365.

Outlook will not open and I get message ''Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The operation failed''.
I can start Outlook in safe MODE by holding down control button. My inbox is all there but my sent items all seem to be missing.
I had to change/redo my profile and was then able to look at inbox etc.
I cannot send EMAILS but all are being received.

This has been going on a few weeks now with me starting in safe mode just to get by.

I am pretty sure it is down to a CORRUPT file.
Is there any way of sorting this out or should I just buy a recovery program - is there a recommended ONE?

(HP Compaq, win7pro sp1, 64bit)Try Here...You're not alone: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_outlook-mso_win10/outlook-2016-will-not-open-error-cannot-start/0e4cfeb6-9797-455d-9b1f-468210b470cc I have tried the repair quick and online & the reset pane - still get same message.

But I do recall how this happened now - I had a power cut and so computer went down.
Then after restarting Outlook would not work.

Anything else I can do?
Will a recovery programme work?Why can't I send emails? (I am still in outlook safe mode)

Emails bounce back with error code

In account settings server requires authentication is ticked.
A test email is sent and says all ok.

But when I send an email it bounces back with code/message...
Server error: '554 5.7.1 : Relay access denied'