There are ways so they don't go into the spam box. Also, gmail is not going to be used nor is my own server due to eventual black listing. Using a major isp will prevent this. If you send out 100 emails daily spread out over 10hr it won't land in the spam box most of the time. The limit is typically 250 emails. Many people send out 50 emails at once and that is where you have problems.
This is for legit marketing purposes sent to targeted business owners hand selected for a new start up im working on. All can-spam laws will be followed such as identifying it's an ad, allowing opt out requests, etc.
The problem ive found with email marketing platforms though is:
1) They have to be opted in through their system, you can't upload a list which did not request it.
2) Lack of emails you can send daily. Ideally, 100k would be sent monthly.