I have several devices through which I read email (via POP 3 or IMAP). The messages are downloaded to each device and remain on the server for 60 days - then are deleted by my principal mail client (now Outlook 2016).

Since installing a new W10 machine with Office 2016, I keep getting locked out of my account. The ISP helpdesk were far from helpful, suggesting a client issue. Indeed, the problem seems to occur whenever I boot my W10 machine. Workaround is to log onto webmail to authenticate - then all is well 'till next reboot.

I have reduced email checks on the main 3 devices (that are always on), to 20 mins - to avoid simultaneous login conflicts, but still the problem occurs.

It appears as though there may be a conflict between Windows Mail and Outlook 2016, but I cannot de-install Mail in preference to Outlook.

Any ideas please?