Interesting the Speigel story ( normally very well informed) it says he email was sent to Vilnius airport at 12:25, so before they entered Belarus airspace. One possible scenario is that they probably thought that Vilnius would inform the crew via company frequency and the crew itself would announce it on on their frequency and would divert "naturally " to closest airport would would be Minsk. But that did not happen and as the aircraft was about to leave their airspace they quickly changed to plan B, only realizing afterwards they had not sent the email to themselves and someone stupidly did it retroactively .
The plot thickens....