 imapsync was successful for me
I actually migrated 23000 accounts in the matter of a weekend using imapsync. Not too sure about the memory issues, our servers have 4 GB in them. Out of 23000 accounts, I've only had a few(maybe a dozen) phone calls of email missing. Maybe it has to do with the way we sync'd mail:
Round 1, all mail in inbox newer than 30 days and also create subfolder structure(but no mail)
Round 2, all mail in subfolders
Round 3, all mail in inbox older than 30 days, but less than 180 and only read mail
Round 4, all mail that has been read and older than 180 days
We are now migrating any other mail on a request basis(and there haven't been many)
We also split our imapsyncs into ~40 processes running simultaneously on multiple machines separate from source and destination servers. Each machine had 2 - 3 imapsyncs running. |