problems with calendar invites

Until very recently I have been successfully using Business Calendar 2 with my account to manage my calendar including sending invites for meetings.

However, I recently reloaded my phone and now I cannot issue meeting invites for this account whether I use BC2, VMBoxer or the stock Android calendar app. I get an error message along the lines 'unable to send one or more messages' although there is nothing in my inbox.

It only works if I use the app which I don't like.

Is this a cunning plan by Microsoft to force me to use their app or have I missed something.

Any advise gratefully received.


David Anning