I landed here when searching "esetmessageflag causing sync issues outlook".
I'm running NOD32 AV 220.127.116.11. This has been an issue for a long time (without me knowing it).
I only just found out after a user reached 98% of 50Gig capacity for their mailbox. There are
over 30,000 messages in the conflicts folder (over 14Gigs).
So there's still no fix, huh?
This is an insane amount of work if someone had to sift through these messages to
see which of the conflicts should be kept. Do we just blindly delete everything in this folder?
This is not a free product.
ESET is left with two choices, fix it or lose customers.