This happened to me last year and I just remember again when I view my PM history. Someone report all my previous post. I received bunch of deleted post notification on my inbox for more than a week then I received temporary ban for 7 days afterwards..

All the post deleted is a decent and not spammy because I’m just disccusing with other user post on the thread with only 2 page. I realize that someone just browse my post history and report all my previous post.

Question: At what certain amount of deleted post will cause a permaban? I lost count because I delete all this notification on my message because it's already annoying at that time.

There is no set number and bans are taken on a case by case basis but bans are rarely given for a set amount of posts deleted. If you're caught spamming and all your posts are very low quality then you might get a temp ban. If you don't take the warning and continue making low quality content you'll usually get another ban with the duration doubled but if you have to be banned three times then the fourth is usually the last one you'll get. Thankfully most don't get that far these days but there's also less bans given out for sig spam. This is something we still should be enforcing at the root cause which is the sig campaigns themselves. If they're paying for this fluff time and time again then they should receive the punishment but that's rare. The only case I can think of recently was yobit. Thankfully most campaigns don't get that bad but yobit was like an avalanche of spam unleashed instantly so they had to be dealt with.