Cannot send authorisation emails after installing O365

We use a purchase order application that sends authorisations via email, it worked flawlessly until we upgraded from Office 2013 Pro to Office 365.

I hasten to add that sending emails via the Outlook 2016 client works fine.

I presume that O365 no longer uses the MAPI client to direct the mail to the exchange server?

I did find several posts about creating a Outlook64Bridge but that did not work.

Also tried the FIXMAPI.EXE tool.

Event Viewer Logs:

Faulting application name: ENTRPRSE.Exe, version: 7.0.5.5598, time stamp: 0x2a425e19
Faulting module name: ntdll.dll, version: 6.3.9600.18895, time stamp: 0x5a4b127e
Exception code: 0xc0000005
Fault offset: 0x0001de33
Faulting process id: 0x604
Faulting application start time: 0x01d402f066224d66
Faulting application path: [MappedDrive]\ENTRPRSE.Exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report Id: d3308bfc-6ee3-11e8-bf94-68f728641a32
Faulting package full name:
Faulting package-relative application ID:

Thank you in advance for any help.

Andrew