A little bit of steam from some boiling water will unstick the flap of an enevelope…
He knows he’s behind and isn’t going to pay anyway.
I think that the official NOD will be sent certified mail and require a signature at delivery, not just first class mail.
When your short lease is up, and house hasn’t gone to sale yet, I’d start to negotiate rent @ $500 a month and see what he says. If you bail, he gets zero until he loses it.
The HOA might go after him personally, has nothing to do with you…
I wouldn’t plan a 4th of July party there just yet, but you’re probably good past the Easter Bunny, and may get Memorial Day weekend there too.