I am migrating to Office 365 from another hosted Exchange provider (www.123together.com), and because we don't have access to our current hosted Exchange server, it appears like the only migration option supported in Office 365 for this configuration would be IMAP.
First question: can anyone say whether this is a true statement, or is there a known way to migrate from another hosted Exchange provider other than with IMAP.
I tried the IMAP conversion approach, and I got the migration batches to work ok, but in some mailboxes it might skip like 800 messages from 4,000 - and there aren't 800 messages that are greater than 35MB each, which is the only criteria that I could find for messages that would be intentionally skipped.
Second question: has anyone had a similar problem to this, and were you able to diagnose the cause and remedy it? Because if I can't, then IMAP migration is not an option.
So in terms of a final approach, I am testing the concept of having each user do an "Export" on their current OST to a "backup.pst" and then "Import" that into the fresh OST on Office 365. I've read some comments that this is the least desirable approach, and of course it means lots of support - although we're a technology company and we only have about 30+ folks, so hopefully it won't be too painful. At least this approach also imports the calendar, notes, tasks and contacts, whereas IMAP wasn't going to solve that problem for me.
Third question: any comments on my final approach to this?
All responses much appreciated.