I have wlm 2012 running on Windows 10/64. Have about 5.5gb of emails to copy across.

Outlook 2016/32 installed and works insomuch as new emails are arriving into it.

However following the procedure for importing emails from wlm2012, I have opened both systems, specify export emails via the microsoft exchange option, the the process starts and then fails after importing 320 of 7500 emails into the inbox (I also do have a number of subfolders which aren't copied across either). tried it twice with the same result. I think these 320 emails are those still on the pop3 servers, is this a clue?

Any suggestions?