I'm late to this particular party, but for reference in my day job (at Loughborough Uni) I recently moved our students from a Google (Apps for Edu | GSuite) domain to Office 365.
That was 17000+ mailboxes, INBOX, subfolders and all, using imapsync with a lot of 'tuning'. I ran it in parallel on a single CentOS 7 VM with 24GB RAM and 12 cores, using delegated access on the O365 side and 'admin' access via XOAUTH2 on the Google side, with a maximum of 130 concurrent jobs. In total it took a shade under 5 days (around 300Mbps bidirectionally). We didn't hit any notable limits at all at either end, but I did land the migration VM in O365's bad books after mis-cueing the authentication end of things during the development phase. They really didn't like getting thousands of auth failures per hour! Graeme _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
