It's actually _not_ because their validation sucks, but because salespeople decided that it means you won't read their newsletter or other spam. They understand

It's actually _not_ because their validation sucks, but because salespeople decided that it means you won't read their newsletter or other spam. They understand the situation as - hi, this is my email please use that subaddress so I can mark it as spam (yes, I know that spam filters don't need subadresses - but try to explain it to an average salesdude - I've tried).