ah, been there, done that, got no tshirt.. but a cease and desist.
Moved from one company to the direct competitor (nothing in the contract saying i couldn't), had three months notice, as some other colleagues who just by chance left at the same time. Everything good, even got a raise offered and better conditions on the last day. As soon as we started the new job some "tech" found the smoking gun, we had downloaded all company data from the cloud storage... yep, it was synced to the laptops, because why bother segregating information, in fact it wasn't donwloaded but the sync tool had to get the list of files... whatever, it took them 5 months and 2 other more or less identical letters to stop bothering us. In the end for whatever reason (like no proof at all) they stopped... Still cost me a good portion nerves and 800€.
anonymous because people carry grudges for a long time and i don't want this to start again.