If a transaction is marked as problematic - I forget the verbiage from the drop-down menu where one chooses "Package Received", "Package Sent", etc. - then after 90 days it will be deleted. However, trades that have not been marked as a problem or as "Transaction Complete" will remain on your "In Progress" tab regardless.
Logging on doesn't mean they've seen emails, and I will say I've had the same experience with Hundomatic as you have, except without an actual deal being made. He's failed to respond to offers or emails over the years with me.
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“Aslan didn't tell Pole what would happen. He only told her what to do. That fellow will be the death of us once he's up, I shouldn't wonder. But that doesn't let us off following the signs.” - Puddleglum in The Silver Chair by C. S. Lewis