And if you end up on a blacklist, even if by mistake? And how do you monitor your system and stats? How do you handle throttling by different MTAs? How are you measuring opens and clicks? How are you managing unsubscribes, and soft and hard bounces? This is not to say that all of this is not something you can't tackle. Instead, many companies prefer to pay a small premium to not worry about any of that and instead focus on their core business.